The reaction shown is a nucleophilic substitution (SN2) where the cyanide ion (CN⁻) attacks the chiral carbon from the backside, inverting its stereochemistry. The reactant has the (R) configuration. Since SN2 proceeds with stereochemical inversion, the product must have the (S) configuration.

The correct product is the one with the inverted stereochemistry: ${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{CH}\left(\mathrm{CN}\right)\mathrm{CH}3$ with the (S) configuration.

Final Answer: The second option.