Answer:
b) Two traits whose appearance varies based on the environmental conditions
Explanation:
A trait may be determined by genes, environment or the interaction of genes and environment. Some traits are not regulated by genes but the environmental conditions of the individuals regulate them. For example, the physical health of humans depends on their eating habits, nutrition, physical exercises, hygiene, etc. A person eating a nutrient rich diet, living under hygienic conditions is more likely to have good health than slum dwellers. Likewise, muscle strength and muscle mass in humans are mostly regulated by physical activities and diet.
