While it was yet dark a great strange cry rang out in the churchyard.

A. Simple
B. Compound-Complex
C. Compound
D. Complex
I know 100% that it isn't simple. I think it is C though. Am I right?

No, not C ... and you're right that it's not A either.

http://www2.ivcc.edu/rambo/eng1001/sentences.htm

No. A compound sentence has two independent clauses.

So is it D?

Yes, D

To determine whether the given sentence is a simple, compound, compound-complex, or complex sentence, we need to understand the structure of each type of sentence.

A simple sentence consists of a single independent clause, which contains a subject and a predicate. It expresses a complete thought. Example: "I went to the store."

A compound sentence consists of two or more independent clauses joined by a coordinating conjunction (such as "and," "but," or "or"). Example: "I went to the store, and my friend went to the park."

A complex sentence consists of an independent clause and at least one dependent clause. A dependent clause cannot stand alone as a sentence because it does not express a complete thought. Example: "Because it was raining, I stayed home."

A compound-complex sentence consists of two or more independent clauses and at least one dependent clause. Example: "I went to the store, but my friend stayed home because it was raining."

Now, let's analyze the given sentence: "While it was yet dark, a great strange cry rang out in the churchyard."

This sentence contains both an independent clause ("a great strange cry rang out in the churchyard") and a dependent clause ("While it was yet dark"). Therefore, it is a COMPLEX sentence (D).

Based on the given options, you are correct in identifying it as a complex sentence (D).