What was thomas hunt morgan's main contribution to science?
a. he discovered that certain traits were linked to the x chromosome.
b. he discovered that certain traits were linked to the y chromosome.
c. he created the first white-eyed female drosophila.
d. he created the first white-eyed male drosophila.

The correct option is A.

Thomas Hunt Morgan contributed to scientific knowledge by studying fruit flies and by discovering through his study that certain traits are linked to the X chromosomes. He discovered this fact, when he noticed that a certain mutation that affect fruit flies' eye color was inherited differently by male and female flies. Based on the pattern of inheritance, Thomas concluded that the gene that is responsible for the eye color is located on the X chromosome.