Question

which is an external environmental factor that affects heredity?
gender
structural differences
nutrition
hormones

Explanation:

To determine the external environmental factor affecting heredity, we analyze each option:

• Gender is a biological trait, not an external environmental factor.
• Structural differences are internal biological features.
• Nutrition is an external factor (from the environment) that can influence gene expression and heredity - related processes (e.g., fetal development, epigenetic changes).
• Hormones are internal biochemical messengers.

So, nutrition is the external environmental factor.

Answer:

C. nutrition (assuming the options are labeled A: gender, B: structural differences, C: nutrition, D: hormones)