Idon't know where the snow came from for there were stars out.

the underlined words in this excerpt are an example of

a noun clause
a relative clause
an adverbial clause
a prepositional clause

The answer is indeed letter C) adverbial clause.

Explanation:

An adverbial clause is a dependent clause that functions as an adverb, modifying a verb, an adjective, or another adverb. It provides information that would answer one of these questions: when? where? why? how? how much? under what condition?

When the adverbial clause answers the question "why", it is called an adverbial clause of reason. It commonly begins with "since" or "because". In the sentence we are studying here, it begins with "for", which is, in this case, interchangeable with the others:

- I don't know where the snow came from for there were stars out.

- I don't know where the snow came from because there were stars out.

As we can see, "for there were stars out" explains the reason why the speaker didn't know where the snow came from.

"get off of your lazy bum and come running with me or i'm dumping this pitcher of water on u " u say with a smile. she thinks your joking so she ignores you about 10 seconds later shes screaming wile water is dripping everywhere you say "here comes the second one! " then you here her say okay, your such a j e r k ! ill be ready in 5 put the pitcher down " she say in an angry tone. and you smile in victory

good enough?