Nos decantamos por la categoría de cultura general.

Because decantarse is a pronominal verb: decantarse por means to opt for / to go for / to lean towards.

So nos is not really ourselves in a literal reflexive sense here. It is part of the verb structure:

• me decanto
• te decantas
• se decanta
• nos decantamos
• os decantáis
• se decantan

In this sentence, nos decantamos means we opted / we opt.

It means to choose in favour of something, to opt for something, or to lean towards something after considering options.

It often suggests there was more than one possibility, and this was the one selected in the end.

So Nos decantamos por la categoría de cultura general gives the idea of:

• there were several categories
• we went for the general knowledge one

It sounds a bit more thoughtful or deliberate than a very basic we chose.

Because decantarse por is the normal fixed combination.

In this expression, por introduces the option that is preferred or chosen:

• decantarse por una opción
• decantarse por un candidato
• decantarse por la categoría de cultura general

So here, por means something like in favour of or for.

A learner should try to remember it as one unit: decantarse por.

It can mean either one, depending on context.

Decantamos is ambiguous in writing because it can be:

• present indicative: we opt / we are opting
• preterite: we opted

So this sentence by itself could mean either:

• We opt for the general knowledge category
• We opted for the general knowledge category

Normally, the surrounding context tells you which meaning is intended.

Because Spanish often drops subject pronouns when they are not needed.

The verb form decantamos already tells you the subject is we, and nos also points to first person plural. So nosotros is usually unnecessary.

You could say:

• Nos decantamos por la categoría de cultura general

and that is completely natural.

If you add nosotros, it would usually be for emphasis or contrast:

• Nosotros nos decantamos por la categoría de cultura general, pero ellos eligieron otra.

Literally, it is the category of general culture, but in natural English it usually means the general knowledge category.

In Spanish, cultura general is a very common expression meaning general knowledge, especially in quizzes, trivia games, exams, or conversations about broad knowledge.

So:

• cultura general = general knowledge
• categoría de cultura general = general knowledge category

Because categoría is a feminine noun in Spanish.

So it takes:

• la categoría
• una categoría
• esta categoría

The ending -ía is a clue here, and the written accent in categoría shows where the stress falls.

Yes. Elegimos la categoría de cultura general is perfectly correct and more straightforward.

The difference is mainly nuance:

• elegir = to choose
• optar por = to opt for
• decantarse por = to lean/go/settle in favour of

Nos decantamos por can sound a bit more like a decision made after considering different options. In Spain, it is a natural expression, especially in neutral or slightly formal speech.

Yes, it sounds natural in Spain.

It is especially natural in contexts like:

• choosing a category in a quiz
• selecting between several options
• making a group decision

In more casual speech, people might also say:

• Elegimos la categoría de cultura general
• Nos quedamos con la categoría de cultura general
• Optamos por la categoría de cultura general

All are possible, but nos decantamos por is a very standard and idiomatic choice in Spain.