Answer: The option that is an example of a simple sentence is C. Animal testing is a cruel way to advance the progress of science.
Explanation: A simple sentence is a sentence that is made up of a single clause, that is to say it is a sentence that has one subject and one predicate. In that way, unlike complex sentences, simple sentences do not include dependent clauses. Option C. is the only one among the options that has a single subject ("Animal testing") and a single predicate ("is a cruel way to advance the progress of science"); therefore, it is also the only simple sentence.
