The correct option is A T. H. Morgan
Linkage is the genetic phenomenon in which two alleles that are located close enough to each other on a chromosome are inherited together. In the year, 1911 Thomas Morgan while studying fruit fly noticed that the two traits (eye colour and body colour of fruit fly) are linked together. He thus hypothesized the concept and termed it "linkage".
Sutton and Boveri independently proposed the chromosomal theory of inheritance and suggested that chromosomes play a very important role as the carrier of hereditary factors. Mendel after working on garden pea postulated the fundamental laws of inheritance.