In a cyclic population
a. populations occasionally increase repidily and then crash to a more stable level.
b. populations increase and decrease in a regular predictable pattern.
c. population fluctuates slightly.
d. population sizes vary.

A population cycle in biology is a process where populations increase and decrease over an anticipated duration of time. There are many classes where population figures have logically anticipated models of reform although the full incentives for population cycles are one of the significant unsolved environmental difficulties.

cats ; snakes

the awnser is d i think