PT 11 S2 Q23

A group of scientists studying calcium metabolism in laboratory rats discovered ... ...

Which one of the following, if true, explains the surprising discovery in a way most consistent with the scientists' hypothesis?
(A) The adrenal gland acts to lower the level of calcium in the blood.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Practice Set: "Resolve/Explain" Questions, Set 2 - Difficult/Uncommon Mix (25Q)