Choose the suitable option for the correct mechanism for the following reactions.

 

(I) High concentration of a good nucleophile is employed, we know the reaction here is an ${\mathrm{S}}_{{\mathrm{N}}^2}$ reaction. Therefore, only one substitution

product is formed theone with the configuration that is inverted relative to that of the reactant.
(II) Because a poor nucleophile is employed, we know the reaction here is on ${\mathrm{S}}_{{\mathrm{N}}^1}$ reaction. Therefore, two substitution Products are formed.