Answer:
The most appropriate explanation would be the presence of two types of melanin in hairs.
In human hairs, two types of melanin are present: eumelanin and pheomelanin.
Eumelanin determines the darkness of the hairs, that is, it would determine if the hairs of a person would be black or brown.
Pheomelanin is responsible for orange or red colors of the hairs. In addition, on breaking down, it provides the hairs with colors like red, orange, yellow and white (complete breakdown of pheomelanin).