Årsaken er klar.

Because årsaken is the definite singular form of årsak.

• årsak = cause / reason
• årsaken = the cause / the reason

In Norwegian, definiteness is often added as a suffix to the noun instead of using a separate word like English the.

No. Here, Å is just the first letter of the noun Årsaken.

A learner may know å as the word placed before an infinitive, like:

• å være = to be
• å spise = to eat

But in Årsaken er klar, Årsaken is a noun, not a verb. The capital Å is simply because it is the first word in the sentence.

Because Norwegian usually marks definiteness directly on the noun:

• årsak = a cause / a reason
• årsaken = the cause / the reason

Using den is not normally necessary here.

You can see den with nouns in more specific structures, especially when an adjective comes before the noun:

• den klare årsaken = the clear reason

But in your sentence, the adjective comes after er, so årsaken by itself is the normal form.

Because adjectives used after er usually agree with the noun in gender and number.

Årsak is a common-gender singular noun, so the correct form is klar.

Compare:

• en årsak → årsaken er klar
• et svar → svaret er klart
• flere grunner → grunnene er klare

So:

• klar = singular common gender
• klart = singular neuter
• klare = plural

Here klar is a predicate adjective, meaning it comes after the verb er and describes the subject.

So the structure is:

• Årsaken = subject
• er = verb
• klar = predicate adjective

This is similar to English:

• The reason
  • is
    • clear

It can mean different things depending on context.

Common meanings of klar include:

• clear / obvious
• ready
• sometimes finished / prepared

In Årsaken er klar, it usually means clear or obvious.

For example:

• Jeg er klar. = I am ready.
• Svaret er klart. = The answer is clear.

So the exact nuance depends on what is being described.

Er is the present tense of å være, which means to be.

So:

• å være = to be
• er = is / am / are

In this sentence, er means is:

• Årsaken er klar. = The reason is clear.

Because this is a normal declarative statement, and Norwegian usually follows subject + verb + complement order here.

So:

• Årsaken = subject
• er = verb
• klar = complement

If you turned it into a yes/no question, the verb would come first:

• Er årsaken klar? = Is the reason clear?

That verb-first pattern is very common in Norwegian questions.

A rough pronunciation guide is:

• Årsaken ≈ OR-sah-ken
• klar ≈ klar with a broad a, not like English claire

A few useful notes:

• å often sounds somewhat like the vowel in British law
• the r is pronounced, though exactly how depends on dialect
• the a in sak is more open than in many English words

A rough full-sentence guide could be:

• Årsaken er klar ≈ OR-sah-ken er klar

Yes. Depending on context, årsak can often be translated as either cause or reason.

• cause can sound more direct or scientific
• reason can sound more general in everyday English

So Årsaken er klar could be understood as:

• The cause is clear
• The reason is clear

Which English word fits best depends on the wider context.

Yes, it is perfectly natural.

It is short, direct, and idiomatic. Norwegian often allows very compact sentences like this.

Depending on context, people might also say similar things such as:

• Grunnen er klar.
• Det er klart hva årsaken er.

But Årsaken er klar is fully natural and correct.