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)

The salivary gland chromosomes in the dipteran larvae are useful in gene mapping because

What is the other name for "incomplete dominance''

The sex in Drosophila melanogaster is determined by

$A $: Non-allosomic genic determination of sex is found in bacteria.
$R$ : Sex is dependent on some environmental factors in prokaryotes.