Which of these could cause the diversity of a rabbit population to increase?
a. if the type of food available to some of the rabbits is different than the food available to the rest of the population
b. if one rabbit gives birth to 6 kits one year, but only gives birth to 4 kits the next year
c. if all of the rabbits eat the same type of food for several generations
d. if a large storm prevents the rabbits from leaving their burrows for several days