Which of the Following Must Be an Assumption of the Mark-Recapture

Which of the following must be an assumption of the mark-recapture method?

A) marked individuals become "trap-happy," relative to unmarked individuals
B) marked individuals avoid recapture, relative to unmarked individuals
C) few individuals enter or leave the study area during the period between mark and recapture
D) the population size changes dramatically between the time of mark and recapture