Over a period of several months, researchers attached small lights to the backs of wetas—flightless insects native to New Zealand—enabling researchers for the first time to make comprehensive observations of the insects' nighttime activities. Thus, since wetas forage only at night, the researchers' observations will significantly improve knowledge of the normal foraging habits of wetas.

Which of the following is an assumption on which the argument depends？

(A) Researchers were interested only in observing the wetas' foraging habits and so did not keep track of other types of behavior.
(B) No pattern of behavior that is exhibited by wetas during the nighttime is also exhibited by wetas during the daytime.
(C)Attaching the small lights to the wetas' backs did not greatly alter the wetas' normal night- time foraging habits.
(D)Wetas typically forage more frequently during the months in which the researchers studied them than they do at other times.
(E)The researchers did not use other observational techniques to supplement their method of using small lights to track the nighttime behavior of wetas.