The mountain areas are barren, but the valleys are fertile since they are irrigated daily. What is the dependent clause

Answer 1

Hint: A dependent clause cannot be a sentence, but it contains a subject and verb. It is not a complete thought but it usually starts with a marker word like "since" or "because".

Answer 2

There are three clauses in that sentence. Two of them are independent clauses; that is, each could be a sentence on its own. One of them is a dependent clause; it cannot be a sentence on its own. I've separated them below. Which one cannot be a sentence on its own?

The mountain areas are barren,
but the valleys are fertile
since they are irrigated daily.