Which of the following is used to hasten the ripening of fruit?

Correct answer: Ethene.

Explanation: Ethene (ethylene, C₂H₄) is a natural plant hormone that triggers ripening in many fruits (e.g., banana, mango, tomato). It stimulates enzymes that soften tissues and convert starches to sugars.

• Ethanol – not a ripening hormone.
• Ethyne – acetylene can mimic some effects but is not the standard/safe ripening agent.
• Ethane – relatively inert; no ripening effect.