(See full question in attachment)
Answer:
A. MeONa
Step-by-step explanation:
One of the methods to prepare alkenes are eliminations.
The E2 reaction (for elimination, bimolecular) occurs when an alkyl halide is treated with a strong base, such as hydroxide ion or alkoxide ion (RO⁻).
It is the most common mechanism that occurs for an elimination.
The methoxide ion is a strong base that will attack the neighboring hydrogen of the halide ion and will start removing H⁺ at the same time that the double bond of the alkene begins to form and the group X begins to leave.
Then, the neutral alkene is produced when the C – H link and X group has left with the electron pair of the bond C – X (mechanism in attachment).
Therefore, MeONa would be an appropiate reagent.