El concursante se decanta por una opción.

Because decantarse por is a pronominal verb in Spanish. In this sentence, the natural expression is decantarse por algo, which means to opt for, to go for, or to lean towards something.

So:

• decantar by itself usually means something else, such as to decant a liquid or to tip/tilt
• decantarse por means to choose in favour of or to show preference for

Here, se is not really translated word-for-word into English; it is just part of the verb expression.

In this sentence, decantarse por means something like:

• to opt for
• to go for
• to settle on
• to lean towards

It often suggests that there were different possible choices, and the person finally shows a preference for one of them.

So El concursante se decanta por una opción suggests that the contestant chooses or favours one option among several.

Because the verb expression is decantarse por. The preposition por is required by this structure.

You should learn it as a chunk:

• decantarse por algo
• optar por algo
• inclinarse por algo

In English, prepositions often do not match Spanish ones exactly, so it is best not to translate them literally.

Yes, but the meaning is slightly different in tone.

• elige una opción = chooses an option
• se decanta por una opción = opts for / leans towards an option

Elegir sounds more direct and neutral.
Decantarse por can sound a bit more nuanced, as if the person is weighing possibilities and then favouring one.

So they are similar, but not always identical in style.

Yes, it is quite natural in Spain. It is used in both everyday and formal contexts.

For example:

• Me decanto por la primera opción.
• El jurado se decantó por el candidato más experimentado.

It is a normal and useful expression in Peninsular Spanish.

It is the present indicative, third person singular.

From the verb decantarse:

• yo me decanto
• tú te decantas
• él/ella se decanta
• nosotros nos decantamos
• vosotros os decantáis
• ellos se decantan

So se decanta means:

• he opts for
• she opts for
• the contestant opts for

depending on the subject.

Because concursante is a noun of common gender. That means the word itself does not change form; the article tells you the gender.

• el concursante = the male contestant
• la concursante = the female contestant

So concursante works for both men and women.

In Spain, concursante usually means a contestant, especially in:

• TV game shows
• talent contests
• competitions
• reality shows

It is very common in media Spanish.

For example:

• Los concursantes del programa
• La concursante fue eliminada

No, that would sound wrong here.

For the meaning to opt for / to lean towards, you need the full pronominal expression:

• decantarse por

Without se, decantar has a different meaning and does not work naturally in this sentence.

So the correct form is:

• El concursante se decanta por una opción.

Because Spanish usually needs an article in cases like this when referring to one option in a general sense.

• una opción = an option / one option

Saying just opción here would sound incomplete.

The sentence presents the option as one member of a set of possible choices, so una fits naturally.

Yes, they are historically related, but you should be careful: the meanings are not always the same in modern everyday use.

In English, to decant usually refers to pouring liquid from one container into another.
In Spanish, decantar can also relate to tilting or pouring, but decantarse por has developed the figurative meaning to opt for or to favour.

So there is a connection, but you should not assume the meanings always match exactly.

They are very close, and in many contexts they can be interchangeable.

• opta por often sounds slightly more straightforward and neutral
• se decanta por can suggest a process of inclination or preference, as if the person is leaning one way after considering alternatives

In many real situations, either would be fine.

For example:

• El concursante opta por una opción.
• El concursante se decanta por una opción.

Both are correct; the second can feel a little more expressive.

You would say:

• Los concursantes se decantan por una opción.

Changes:

• El → Los
• concursante → concursantes
• se decanta → se decantan

If you want the options to be plural too, you could say:

• Los concursantes se decantan por unas opciones.

But in many contexts, una opción still makes sense if each contestant chooses one option individually.