The sentence in question is a simple sentence, as it contains one main clause with both a subject and predicate, expressing one complete thought without additional subordinate clauses. The correct answer is option A.
The sentence 'Sally loves to read books.' is a simple sentence. The correct answer is option A.
This is because it contains one main clause which includes a subject (Sally) and a predicate ('loves to read books') expressing a single complete thought.
The sentence does not have multiple main clauses or any subordinate clauses, which are characteristic of compound and complex sentences, respectively.