Identify the compound '$$\mathrm{A}$$' in the following sequence of reactions.

$$\text { A } \xrightarrow[\text { Dryether }]{\mathrm{C}_2 \mathrm{H}_3 \mathrm{MgBr}} \mathrm{B} \xrightarrow{\mathrm{H}_3 \mathrm{O}^{+}} \text {3-Methylpentan-3-0l }$$

Which of the following is Clemmensen reduction?

Identify substrate 'A' in the following reaction.

2nA $$\mathrm{\buildrel {Dimethyl\,cadmium} \over \longrightarrow}$$ 2n Propanone + n Cadmium chloride

Identify the reaction in which carbonyl group of aldehydes and ketones is reduced to methylene group on treatment with hydrazine followed by heating with sodium hydroxide in ethylene glycol.