In genetics, offspring inherit one allele (gene variant) from each parent for each trait. If the diagram is meant to show a typical Mendelian inheritance pattern, it would typically display different combinations of alleles that can influence a characteristic like hair color.
Given the options:
- one gene for blonde hair
- one gene for brown hair
- two genes for blonde hair
- two genes for brown hair
Assuming the parents have genes for different hair colors, the description that logically would complete the diagram would depend on the traits being modeled. If the parents have different hair colors, then a mixture of alleles would result in:
- If one parent has blonde hair and the other parent has brown hair, the offspring might inherit one gene for blonde hair and one for brown hair, but none of the options directly express that.
The options given simplify to:
- If the offspring description is to be representative of already having two parents with one recessive and one dominant trait, then "two genes for brown hair" might represent the dominant trait (assuming brown hair is dominant over blonde).
However, without the specific context of who the parents are and their genetic makeup, it's difficult to definitively choose one. But if using a dominant/recessive system where brown is dominant, then "two genes for brown hair" would likely be the best fit for an offspring description.