Silver Mirror test is given by which one of the following compounds?

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $3$-chloro-$2$-methylpentan-$3$-one can be subjected to Wolff-Kishner reduction to give $3$-chloro-$2$-methylpentane.
Reason $R$: Wolff-Kishner reduction is used to convert $C=O$ into $CH_2$.

$CH_{3}CH_{2}CN$ $\xrightarrow[Ether]{CH_{3}MgBr} A$ $\xrightarrow{H_{3}O^{+}} B$ $\xrightarrow[HCl]{Zn-Hg} C$
The correct structure of $C$ is

In the above reaction,which of the following will be obtained in maximum yield?

Which of the following reactions cannot be used to convert $R_2CO$ to $R_2CH_2$?

If formaldehyde and potassium hydroxide are heated,then we get