When Thomas Hunt Morgan crossed his red-eyed F₁ generation flies to each other, the F₂ generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?
A) The involved gene was on the X chromosome
B) The involved gene was on the Y chromosome.
C) The involved gene was on an autosome.
D) Other in.ilc-spccific factors influence eye color in flies
E) Other fc.nalc-sjxcific factors influence eye color in flics.

Thomas Hunt Morgan performed the experiment in 1910 on the Drosophila which explained the role played by the chromosomes in heredity. When Morgan crossed red-eyed flies he observed that F₂ flies included both red ad white-eyed flies in which the males are white-eyed only.

Morgan concluded that the genetic factor which controlled the eye color was present on the same chromosome which determined the sex of the flies. This indicated that the gene in involved on the X chromosome and the male is hemizygous for the trait.

Thus, option-A is the correct answer.