Answer:
The answer to your question is "complex sentence" (c).
Explanation:
A complex sentence has one independent clause and at least one dependent clause. The difference between an independent clause and a dependent one is that independent clauses can stand alone as a sentence as they represent a complete thought. Dependent clauses fail to do so, they depend on the independent one to complete their meaning (1).
1) *When the cake is brown, (dependent clause)
2) Take it out of the oven
As you can see, the dependent clause does not make up a grammatical sentence.
