Tertiary carbon in alkyl halide forms carbocation Steps:

• Identify the carbon: In 1-chloro-1-methylcyclohexane, the carbon at position 1 bonds to Cl and three carbons (two from ring, one from methyl), making it tertiary.
• Recognize reaction context: At Z, likely the SN1 carbocation intermediate after Cl departure.
• Determine charge: Loss of Cl⁻ leaves the tertiary carbon with a positive charge.
• Confirm: Tertiary carbocations bear a full +1 charge due to electron deficiency.

Why D is correct:

• By definition, a carbocation has a trivalent carbon with a +1 formal charge (6 valence electrons, octet incomplete).

Why the others are wrong:

• A: Full negative charge applies to carbanions, not carbocations.
• B: Partial negative charge occurs on electron-rich atoms, opposite of carbocation.
• C: Partial positive charge describes polar bonds, not full charge in carbocation.

Final answer: D