SN1 mechanism depends on haloalkane structure and carbocation stability

Steps:

• Classify each haloalkane as primary, secondary, or tertiary based on the carbon attached to the halogen.
• Recall that SN1 reactions occur via carbocation intermediates, favored in polar protic solvents like aqueous NaOH for tertiary halides due to stable 3° carbocations.
• Eliminate primary and secondary halides, which prefer SN2 mechanisms under these conditions.
• Select the tertiary haloalkane as the one proceeding mainly by SN1.

Why C is correct:

• Option C is a tertiary haloalkane, forming a stable tertiary carbocation intermediate as per Markovnikov's stability rule for carbocations.

Why the others are wrong:

• A is primary, favoring SN2 due to backside attack without carbocation.
• B is secondary, typically undergoing SN2 with NaOH(aq) despite some SN1 possibility.
• D is primary or secondary, proceeding via SN2 mechanism.

Final answer: C