A chemist, I. M. Shoddy, has just purchased some compounds in a going-out-of-business sale from Pybond, Inc., a cut-rate chemical supply house. The company, whose motto is “You get what you pay for,” has sent Shoddy a compound A at a bargain price in a bottle labeled only “C₆H₁₀.” Unfortunately, Shoddy cannot remember what he ordered, and he has come to ask your help in identifying the compound. Compound A is optically active and has an IR absorption at 2083 cm^-1. Partial hydrogenation of A with 0.2 equivalent of H₂ over a catalyst gives, in addition to recovered A, a mixture of cis-2-hexene and cis-3-hexene. Identify compound A, and explain your reasoning.