Answer
The major product is cis-2,3-epoxyhexane.
Work Step by Step
The epoxide ring is form across the double bond. MCPBA epoxidizes an alkene by a concerted electrophilic reaction where several bonds are broken and several are formed at the same time. Starting with the alkene and MCPBA, a one-step reaction gives the epoxide and the acid directly, without any intermediates.
Since the reaction happens concerted, the product retains the stereochemistry.
