Conjugated diene undergoes 1,4-addition with HBr

Steps:

• Compound X is a conjugated diene, allowing electrophilic addition of two HBr molecules.
• First HBr adds via protonation at one double bond, forming a resonance-stabilized allylic carbocation.
• Bromide attacks the carbocation at the 1,4-position (major) or 1,2-position (minor).
• Second HBr adds to the remaining double bond in the 1,4-product, yielding the saturated dibromide.

Why A is correct:

• A shows the 1,4-dibromide product, following Markovnikov's rule for conjugated systems where the major pathway stabilizes the allylic intermediate.

Why the others are wrong:

• B: Represents 1,2-addition product after first HBr, ignoring second addition.
• C: Shows anti-Markovnikov orientation, violating regioselectivity in HBr addition.
• D: Depicts a non-conjugated or incorrect skeletal structure, not matching diene reactivity.

Final answer: A