Complete linkage is observed in.....

Thomas Hunt Morgan and his colleagues performed experiments on which organism to verify the chromosomal theory of inheritance and later demonstrated linkage?

$A$ test cross of an $F_1$ fly $+a/+b$ produces the following offspring:
$++/ab = 9$
$ab/ab = 9$
$+b/ab = 41$
$a+/ab = 41$
What is the distance between the linked genes?

Why did Morgan work with the fruit flies $(Drosophila \text{ } melanogaster)$?

Continuous variations are attributed to

Who performed the first experiment on linkage and recombination?