Answer:
b. Morgan—molecular genetics
Explanation:
Thomas Hunt Morgan's research led him to formulate the chromosomal theory of heredity rather than molecular genetics and earned him the Nobel Prize in Medicine in 1933.
In Columbia, Morgan began studying heredity with a team of students, experimenting with Drosophila ampelophila and Drosophila melanogaster, which proved Mendel's theories and allowed us to determine the principles of genetics.
Morgan proved the reality of genes as corporeal elements of specific location on chromosomes. He described the gene system in Mechanism of mendelian heredity, published by his team in 1915.
Morgan's subsequent discoveries concern mutation and hereditary functions of chromosomes.
