What is it called when certain species have evolved such intimate symbiotic relationships that individuals of either species cannot survive without one another?

a. obligate

b. parasitic

c. mutualistic

d. facultative

A. Obligate

Explanation:

An obligate relationship is one where both organisms are interdependent with one another in a way that one cannot survive without the other.

A parasitic relationship is where one organism benefits, and the other is harmed.

A mutualistic relationship is one where both organisms "work together," therefore benefiting one another.

A facultative relationship is where both species benefit off of one another, but are not fully dependent on one another to the point they cannot survive without their symbotic partner.

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.