Which of the Following Statements Best Describes What Is "Relative

Multiple Choice

Which of the following statements best describes what is "relative" in the theory of relativity?

A) The theory says that everything is relative.
B) The theory says that the speed of light is relative,and depends on who is measuring it.
C) The theory says that truth can never be established in any absolute sense.
D) The theory says that measurements of motion make sense only when we state what they are measured relative to.