Which ex below is an ex of allelic frequency?
a. The skin of a population of Caucasian students gets darker during the summer and lighter during the winter.
b. 1 in 2,500 Caucasians are affected by an inherited disorder called cystic fibrosis.
c. African Americans made up 12.3% of the U.S. population in the year 2000.
d. b and c.
e. All of the above.