A gene family has been identified that has undergone extensive duplication in humans but is present in only one or a few copies in other primates or other mammals. What experimental approaches could be used to determine the function of this gene and its significance in human evolution?

• A. Reduce the number of copies of this gene in a human subject.
• B. Determine the timing and location of expression of these genes during embryonic development in fruit flies.
• C. Introduce these genes into yeast and study the phenotype of the resulting cells.
• D. All of the listed responses are correct.
• E. Create knockout mice to determine their phenotype.