Which of the following is least reactive towards nucleophilic substitution reaction?

Which one of the following is used to obtain the maximum percentage of terminal alkene by dehydrohalogenation of $CH_3CH_2C(CH_3)_2Br$?

$CH_3Br + Nu^{-} \rightarrow CH_3-Nu + Br^{-}$
The decreasing order of the rate of the above reaction with nucleophiles $(Nu^{-})$ $A$ to $D$ is
$[Nu^{-} = (A) \, PhO^{-}, (B) \, AcO^{-}, (C) \, HO^{-}, (D) \, CH_3O^{-}]$

Which among the following is most common in alkyl halides?

Which of the following statements is incorrect for a bimolecular nucleophilic substitution reaction $(S_{N}2)$?

Predict the product of the following reaction:
(Image: $A$ chiral carbon attached to a phenyl ring with a para-chloro group,a deuterium atom $(D)$,a hydrogen atom $(H)$,and a chlorine atom (Cl) in a specific stereochemical configuration. The reaction is with $NaI$ in acetone.)