2-Bromobutane is heated with alcoholic KOH. According to Saytzeff's rule the major product is

Abut-1-ene
B(Z)-but-2-ene
Cbutane
D(E)-but-2-ene

Answer: D

Alcoholic KOH causes E2 elimination, giving the more substituted (more stable) alkene as major product. This is but-2-ene, and the E isomer is more stable than the Z isomer because of less steric repulsion.

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