Horses and donkeys are diploid organisms. A horse has 64 total chromosomes, where a donkey has 62. A cross between a female horse and a male donkey produces a mule, which is usually sterile. There are chromosomes in an egg produced by the horse, chromosomes in a sperm produced by the donkey, and total chromosomes in an offspring mule.

There are 32 number of chromosome in egg cells of female horse while 31 number of chromosome in sperm of male donkey so the offspring produce from this fusion is mule having 63 number of chromosome.

Explanation:

Sperm and egg cells are the type of sex cells that contain half number of chromosome. Total number of chromosomes in horse is 64 and its half is 32 while total number of chromosome in donkey is 62 and its half is 31. So the mule have 63 number of chromosome.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".