Answer:
A complex sentence
Step-by-step explanation:
A complex sentence is a type of sentence made up of one independent clause (a clause that expresses a complete thought) and at least one dependent clause (a clause that can not stand alone as a sentence because it does not express a complete thought).
In this type of sentence, the dependent clause is often introduced by a coordinating conjunction such as when, after, while, because, if and until, which also indicate the subordination of the clause to the independent clause.
Here are some examples (independent clauses are underlined and dependent clauses are not underlined):
When Mike left the room, Vanessa started crying.
I usually tell my child stories at night until he falls asleep.