The correct answer is C) What kind of seeds do cardinals like to eat best?
Step-by-step explanation:
In science, a testable question is a question that can be answered through experiments or tests, and by following the scientific method. In the case of Sally, the best question for her is "What kind of seeds do cardinals like to eat best?" because this question addresses the main phenomenon she wants to study that is the cardinals' feeding habits or what cardinals eat. Also, this question is testable because Sally can discover the answer by placing different kinds of seeds and observing which ones Cardinals choose.