The decreasing order of nucleophilicity among the nucleophiles

(A) ${\text{CH}}_3\underset{O}{\underset{\left|\right|}{\text{C}}}-{\text{O}}^{-}$

(B) ${\mathrm{CH}}_3{\mathrm{O}}^{-}$

(C)  ${\mathrm{CN}}^{-}$

(D) 

$2-$chloro$-2-$methylpentane on reaction with sodium methoxide in methanol yields :

The major product obtained in the following reaction is :

The increasing order of the reactivity of the following halides for the Snt reaction is :

The major product of the following reaction is

The major product of the following reaction is :

The major product of the following reaction is