Why did thomas hunt morgan use fruit flies in his studies?

Thomas Hunt Morgan used fruit flies to study genetics for several reasons. First, fruit flies have a short life cycle that lasts an average of just 30 days. This means genetic traits can be studied over dozens of generations in the course of a year. This rapid reproductive cycle is impossible to match in any mammalian model, even mice or rats. Second, fruit flies produce huge numbers of offspring.

well, i believe that the answer is 2. : 3