The Starting Point of Scientific Inquiry Is Asking Scientifically Testable

The starting point of scientific inquiry is asking scientifically testable questions. Which of the following is such a question?

A) "Why does my brother like Star Wars rather than Star Trek?
B) "How do people know when it's their turn to talk when in conversation with others?"
C) "Why does my family always choose to go north for summer vacation?"
D) "When do brown shoes make more sense than black shoes?"
E) "What's up with jumbo shrimp?"