What is the probability of a couple having four sons?

$A$ diploid organism is heterozygous for $5$ loci and homozygous for $2$ loci,how many types of gametes can be produced?

If Mendel had studied $7$ pairs of traits in a plant with $12$ chromosomes instead of $14$,then:

Out of the $7$ pairs of contrasting traits selected by Mendel,how many traits were related to the pea pod?

The branch of zoology dealing with the study of similarities and differences between individuals related by descent is known as:

Mendel published his work on the inheritance of characters in $1865$,but it remained unrecognized until $1900$ 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 his contemporaries.
$(c)$ Mendel's approach of using mathematics to explain biological phenomena was considered ahead of its time and unconventional.
$(d)$ Communication was not easy (as it is now),and his work could not be widely publicized.