
Passage: Recently, hundreds of seals died after eating a type of fish contaminated with chemicals. This chemical can poison mammals even in small amounts. However, some people ate the fish without getting poisoned.
Question: Which of the followings, if true, helps most to explain the contradiction in the statement above?
A. A.Fish contaminated with this chemical was not harmed by the chemical itself.
B. B.Toxic chemicals gathered in the parts of the fish that seals eat but humans don't.
C. C.Trace amounts of this chemical poison have also been found in the bodies of some people who neither eat fish nor fish products.
D. D.Fish contaminated with the chemical made up only a tiny fraction of the seals' total food intake.
Answer: