Why Did Scientists Inject Genes Encoding for a Green Fluorescent

Why did scientists inject genes encoding for a green fluorescent protein into rhesus monkeys?

A) Glowing green rhesus monkeys would be popular in zoos or as pets.
B) The green protein treats an immunodeficiency disease in the monkeys similar to AIDS.
C) It was a mutation that was easily seen in subsequent generations of the monkeys so it could be traced as it passed through the family, illustrating inheritance patterns.
D) Rhesus monkeys cannot see the color green so the mothers would not reject any green babies.
E) The monkeys' biology is similar to humans and they were trying to develop methods to insert disease genes into the monkeys so the diseases could be studied.