Answer:
Contains large polytene chromosome that permit visual inspection of genomic events.
Were used to study the genetic effects of mutations.
Were used to establish the concept of chromosomal inheritance.
Step-by-step explanation:
Drosophila melanogaster is a model organism that is used by scientists to study the genes and effect of a mutation on the genes. Drosophila is used as a model organism as it has a very short life cycle and the offspring can be produced in a short duration of time.
Because of these characteristics, Thomas Hunt Morgan wanted to study the factors of inheritance on the Drosophila and concluded in the form of the chromosomal theory of inheritance by the effect of mutation on genes that lead to linkage mapping.
Also, the salivary gland of fruit fly contains the polytene chromosome which allows us to look into the gene events.
Thus, the selected options are correct.