The total number of monohalogenated organic products in the following (including stereoisomers) reaction is

$$\begin{gathered} \underset{(\mathrm{Simplest} \mathrm{optically} \\ \mathrm{active} \mathrm{alkene})}{\mathrm{A}} \underset{\left(\mathrm{ii}\right) {\mathrm{X}}_2/∆}{\overset{\left(\mathrm{i}\right) {\mathrm{H}}_2/\mathrm{Ni}/∆}{\to }} \end{gathered}$$

consider the above reaction, and choose the correct statement:

Presence of which reagent will affect the reversibility of the following reaction, and change it to a irreversible reaction :

$\mathrm{C}{\mathrm{H}}_4+{\mathrm{I}}_2\underset{\mathrm{Reversible}}{\overset{\mathrm{hv}}{\rightleftharpoons }}{\mathrm{CH}}_3-\mathrm{I} + \mathrm{HI}$

Which one of the following is the major product of the given reaction?

In the following sequence of reactions, the final product $\mathrm{D}$ is:

For the given reaction:

What is $\mathrm{A}$?