This is a nucleophilic substitution reaction where the cyanide ion (CN⁻) attacks the chiral carbon. Since the substrate is a secondary alkyl halide, the reaction proceeds via SN1 mechanism with carbocation intermediate. The carbocation is planar, allowing nucleophile attack from both sides, resulting in racemic mixture (50% R and 50% S enantiomers).

Racemic mixture formation: $\frac{1}{2}$ R + $\frac{1}{2}$ S.

Final Answer: Option 3 (racemic mixture)