Major product of the following reaction is:

• Regioselectivity (Markovnikov's Rule): The electrophile ($$\text{D}^+$$) attacks the less substituted double-bonded carbon to form the more stable tertiary carbocation at the methyl-bearing carbon center.
• Nucleophilic Attack: The chloride ion ($$\text{Cl}^\ominus$$) then attacks the planar, $$sp^2$$-hybridized carbocation from either the top or bottom face with equal probability.

Conclusion:

Because the nucleophile can attack both faces of the intermediate carbocation, a racemic mixture ($$\pm$$) of cis and trans stereoisomers is formed.

Answer: Option C