After an oil spill, rehabilitation centers were set up to save sea ott

After an oil spill, rehabilitation centers were set up to save sea otters by removing oil from them. The effort was not worthwhile, however, since 357 affected live otters and 900 that had died were counted, but only 222 affected otters, or 18 percent of those counted, were successfully rehabilitated and survived. Further, the percentage of all those affected that were successfully rehabilitated was much lower still, because only a fifth of the otters that died immediately were ever found.

Which one of the following, as potential challenges, most seriously calls into question evidence offered in support of the conclusion above?

(A) Do sea otters of species other than those represented among the otters counted exist in areas that were not affected by the oil spill?

(B) How is it possible to estimate, of the sea otters that died, how many were not found?

(C) Did the process of capturing sea otters unavoidably involve trapping and releasing some otters that were not affected by the spill?

(D) Were other species of wildlife besides sea otters negatively affected by the oil spill?

(E) What was the eventual cost, per otter rehabilitated, of the rehabilitation operation?