Question

When Sara turned her homework in, she forgot to put her name on it.

Answer 1

I believe that the answer would be A, Simple. I researched the different definitions of all of the types, I will provide you with each of them. (Source; Google)

1)  Simple- a sentence consisting of only one clause, with a single subject and predicate.
2) Conjoined - has two (or more) clauses joined together using coordinating conjunctions (and, but, or …) E.g. Zubair fell and twisted his ankle.
3) Complex- a sentence containing a subordinate clause or clauses.
4) Compound- a sentence with more than one subject or predicate.

Hope this helps!