Which of the following, if true, most seriously calls into question the exterminator's claim that the absence of signs for three weeks means the mice have been eradicated by the poison? A. Because mice hide whenever they sense humans, it is very difficult to see or hear mice even when there is an active infestation. B. It is more humane to use "live-catch" traps that allow homeowners to release the still-living mice outside. C. In the spring, many mice that nest in houses begin foraging for food outside and do not return to the comfort of the house until the fall or winter. D. There are several different kinds of poison that could be used, some of which are more effective than others. E. It sometimes takes longer than three weeks for all of the mice to ingest and die from the poison.