It can be inferred from the passage that the author assumes which of the following in the discussion of the rate at which IRC+10216 loses mass? A. The circumstellar cloud surrounding IRC+10216 consists only of CO and NH3 molecules. B. The circumstellar cloud surrounding IRC+10216 consists of material expelled from that star. C. The age of a star is equal to that of its circumstellar cloud. D. The rate at which IRC+10216 loses mass varies significantly from year to year. E. Stars with a mass greater than 6 Mʘ lose mass at a rate faster than stars with a mass less than 6 Mʘ do.