TOEFL Reading: ETS-TOEFL阅读机经 - IU8II71D6Q11XW6ZL$

Paragraph 4 suggests that for primitive termites, a major advantage of nesting inside a rotting tree is that a rotting tree A. is a very easy site to excavate B. provides a ready source of wet cellulose C. provides a lot of raw material for making carton D. helps preserve stored food