Answer:
c. affects genotypic expression of characters.
Step-by-step explanation:
Environmental variation like food, variation, humidity, oxygen, etc affects the expression of characters which is seen in the phenotype. For example, in crocodiles and some reptiles, the incubation temperature in which their eggs are present determines the sex of their offspring.
This shows that temperature affects their genotype and allow expression of some genes more which can be seen in their phenotype. Therefore environmental variation plays an important role in the expression of characters by affecting genotype.