John Wingfield and His Coauthors Made the Following Statement Early

John Wingfield and his coauthors made the following statement early in their article on testosterone and the challenge hypothesis: "The prevailing 'challenge' hypothesis asserts that testosterone and aggression correlate only during periods of heightened interactions between males." This statement is a

A) definition of the challenge hypothesis.
B) prediction derived from the challenge hypothesis.
C) statement about the evidence that supports the challenge hypothesis.
D) scientific conclusion.