Final answer:
Human eye color is influenced by multiple genes beyond just bey2 and gey, leading to a wide array of possible colors through complex inheritance patterns. Green-eyed children can be born to brown-eyed parents if both parents carry a recessive green allele, exemplifying non-Mendelian genetics.
Step-by-step explanation:
Human eye color is a trait determined by the intricate interplay of multiple genes. The genes bey2 and gey are known to be involved in this process, creating the common eye colors of brown, green, and blue. But when it comes to other eye colors such as hazel, grey, and amber, it is a matter of complex inheritance patterns or non-Mendelian inheritance. This means that multiple genes, each with two or more alleles, contribute to the phenotype of a single characteristic.
To illustrate how eye colors like green can appear in children even when both parents have brown eyes, we can refer to the principles of genetics. Assuming that brown is a dominant trait over green, the parents can both be heterozygous, meaning they possess one allele for brown and one for green. When each parent contributes a green allele to the child, it results in the child having green eyes, as there is no dominant brown allele to mask the green.
Thus, the correct answer to how both brown-eyed parents could produce a green-eyed child is b. Both parents are heterozygous, having the green trait on the green-blue eye gene.