Propyne is allowed to react with ${\mathrm{B}}_2{\mathrm{D}}_6$. The product is treated with acetic acid. The final product formed is

The order of decreasing reactivity towards an electrophilic reagent, for the following
(A) Benzene
(B) Toluene
(C) Chlorobenzene and
(D) Phenol

would be

In the sulphonation of benzene, the active electrophilic species is:

Consider the following reaction:

$\mathrm{R}-\mathrm{CH}={\mathrm{CH}}_2+{\mathrm{IN}}_3^{}\to \mathrm{A},\mathrm{A}$ is:

 product; product will be:

 major product will be:

The most probable structure for $\left(\mathrm{P}\right)$ in the following reaction is: