The presence of microorganisms that produce a toxin causes
seawater to turn brownish red, phenomenon known as a red tide. Sea
otters do not feed in areas where clams, their main source of food,
have become contaminated with this toxin. According to a proposed
explanation of the otters' behavior, the otters sample the clams in a
potential feeding areas and can taste any toxin in them.
Which of the following, if true, would most strongly indicate that
the hypothesis described in the last sentence of the passage is not
(A) In some of the areas where red tides occur, neither clams nor sea
otters are indigenous species.
(B) The presence of sea otters in a given areas has a significant
effect on which other marine organisms are to be found in that area.
(C) When seawater in an area unaffected by red tide is artificially
dyed brownish red, sea otters do not feed on the clams in that area.
(D) If the clams in a given area are contaminated with toxins, sea
otters move to other areas in search of food.
(E) Although very small amounts of the toxin produced during a red
tide are not harmful, large doses can be fatal to animals the size of