Question

Some lizards can undergo both sexual and asexual reproduction. Being able to reproduce asexually benefits the organism during times when mates are hard to find. Under what circumstances would asexual reproduction be most beneficial?

a The species finds its life span is increasing rapidly.
b The species finds itself falling prey to a new and well-adapted predator.
c The species needs to adapt to a dwindling source of food.
d The species needs to develop resistance to a new type of disease.

Answer 1

A would decrease the need for reproduction, so that's not it.
C wouldn't be helpful - less food wouldn't want you to produce more organisms, it would mean more competition for less food
D wouldn't be helpful, asexual reproduction creates a limited gene pool that is less likely to be resistant to diseases
So B is the answer, because the more of the species there are, the greater chance of survival. 

Answer 2

I did the test and the answer was B.  The species finds itself falling prey to a new and well-adapted predator.