When Mendel self hybridised the ${\mathrm{F}}_1$ plants $\left(\mathrm{RrYy}\right),$ he found that dominant and recessive traits of one character are segregated in a

Mendel published his work on inheritance of characters in 1865, but it remained unrecognised till 1900 because

(a) He could not provide any physical proof for the existence of factors.
(b) His concept of factors as stable, discrete units that controlled the expression of traits did not find acceptance from the contemporaries.
(c) Mendel's approach of using mathematics to explain biological phenomena was totally old.
(d) Communication was not easy (as it is now).

Fruit flies are one of the best materials for genetic studies because of all, except