Under What Conditions Are Asexual and Sexual Reproduction Favored by the Three

Under what conditions are asexual and sexual reproduction favored by the three evolutionary models,involving environmental unpredictability,number of niches,and parasite load?
A)Low environmental unpredictability
B)High environmental unpredictability:
C)Low number of niches
D)High number of niches
E)Low parasite load
F)High parasite load