A Horse Has 2n = 64 and a Donkey Has

Multiple Choice

A horse has 2n = 64 and a donkey has 2n = 62. The hybrid of these two species, the mule, has 63 chromosomes and is sterile. Why are mules sterile?

A) Their zygotes cannot complete the first mitotic division to form the two-cell stage.
B) They cannot physically mate with each other.
C) They cannot physically mate with horses and donkeys.
D) They lack homologous chromosomes and cannot undergo meiosis.