The correct answer is that variable number repeats are used in DNA tests; they have hundreds of possible lengths. Eye color is determined by variations in a person's genes. Most of the genes associated with eye color are involved in the production, transport, or storage of a pigment called, melanin. Eye color is directly related to the amount and quality of melanin in the front layers of the iris.
The system that is responsible for breaking down food and releasing essential nutrients and other substances that the body needs and requires is the digestive system.