Which of the following is the main category of mutation

To store blood some anticoagulant is added. It can be

In Cooley's Anemia, the affected chain of a haemoglobin is

The gene which increases the frequency of mutation in other gene is referred to as

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)