Which halide will be least reactive in respect to hydrolysis?

The major products $X$ and $Y$ respectively from the following reactions are:

The major product of the following reaction is:
$C_6H_5-CH_2-C(Br)(CH_3)-CH_2-CH_3 \xrightarrow[C_2H_5OH]{C_2H_5ONa}$

The decreasing order of reactivity of the following compounds towards nucleophilic substitution $(S_{N}2)$ is :

Given below are two statements:
Statement $I$ : $C_2H_5OH$ and $AgCN$ both can generate nucleophile.
Statement $II$ : $KCN$ and $AgCN$ both will generate nitrile nucleophile with all reaction conditions.
Choose the most appropriate option :

Which of the following compounds gives a racemic mixture on nucleophilic substitution?
$(a)$ $CH_3-CH(Br)-C_2H_5$
$(b)$ $CH_3-C(Br)(CH_3)-C_2H_5$
$(c)$ $C_2H_5-CH(C_2H_5)-CH_2Br$