What must occur to enable the group of breeding organisms

male and female creatures and their reproductive system should function well in order to breed..

for human,attraction should occur..

the production of offsprings

Explanation:

The production of offspring, or , must occur to enable the group of breeding organisms, or , to continue to exist. ... Any inherited characteristic, or , developed in a species over time can enhance the species' ability to survive and produce offspring in its environment.

the contamination

we are putting to many trash.

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.