Which one of the following was the rediscoverer of Mendel's work?

$A$ human male is heterozygous for autosomal genes '$A$' and '$B$'. He is also hemizygous for the haemophilic gene '$h$'. What percentage of sperms will carry the '$abh$' genotype (in $\%$) (in $\%$)?

Mendel studied . . . . . . pure breeding traits of Pisum sativum.

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: In an experiment, Mendel observed that the $F1$ progeny plants are all tall and none are dwarf.
Reason $R$: Stem height is a contrasting trait, with tall being dominant and dwarf being recessive.
In the light of the above statements, choose the most appropriate answer from the options given below:

The law of dominance is used to explain the expression of only one of the parental character in a monohybrid cross in $........$ generation and the expression of both in $........$ generation.

The cause of variation is hidden in the process of $.....P.....$ - this knowledge was acquired by humans in $.....Q.....$.
$\quad \quad P \quad\quad\quad Q$