What question does the adverb clause answer?

after i went to bed last night, the telephone rang twice.

when
where
how
why
under (on) what condition
compare/contrast

When

Explanation:

Clause is a group of words that usually consists of subject and predicate. There are two types of it: independent ( it can stand alone as a sentence) and dependent ( it can not stand alone). Types of dependent clause: adverb, adjective, noun dependent clause. Adverb clause modifies the meaning of a verb, adjective, another clause etc.  It usually starts with although, if, after...

In the given sentence adverb clause is After I went to bed last night and it answers the question when did the telephone ring.

my answer is the spanish won