题目选项分析

Scientists have discovered a new species of butterfly that lives only in a small region of Central America and is active only at night. During the day, it rests in treetops, where its green color matches the foliage perfectly. Therefore, the scientists must have discovered the butterfly at night.

The argument depends on which of the following assumptions?

【选项】 There is no way for the scientists to detect the butterfly during the day.