CR question, difficult one

[Jason.tuyj]

Regulations will not allow a pesticide that is toxic to humans to be used inside houses unless the pesticide will dissipate completely from the air within eight hours after its application. One test that pesticide manufacturers standardly use to determine how quickly anti-termite pesticides dissipate involves spraying the pesticides on the walls of room-sized plywood boxes and then timing its dissipation.

Which of the following would it be most useful to know in order to evaluate whether a dissipation time of just under eight hours on the manufacturers’ test indicates that an antitermite pesticide that is toxic to humans obeys regulations for use in houses?

A. Whether anti-termite pesticides dissipate more slowly in furnished rooms than in plywood boxes

B. Whether people who apply anti-termite pesticide standardly wear protective equipment that prevents them from being exposed to the pesticide

C. Whether people whose house is being treated with anti-termite pesticide generally know that they should remain out of their house during the hours immediately after the pesticide’s application

D. Whether there are anti-termite pesticides that are toxic to humans that, when subjected to the manufacturers’ test, dissipate completely from the air in the boxes in well under eight hours

E. Whether anti-termite pesticides that are not toxic to humans tend to take longer to dissipate than those that are toxic

Why B and D are out, pls explain explicitly. I know why A is right!

[jnelson0612]

What is the original source of this question?