The gas used for artificial ripening of green fruits is

The correct answer is (d) Ethylene.

Ethylene is a gas that is produced naturally by fruits as they ripen. It can also be artificially produced and used to ripen fruits that are not yet ripe. Ethylene works by stimulating the production of enzymes that break down the cell walls of fruits, causing them to soften and ripen.

Ethane, carbon dioxide, and acetylene are all gases that are found in the atmosphere. However, they do not have the same effect on fruits as ethylene does. Ethane and carbon dioxide can actually slow down the ripening process, while acetylene can cause fruits to rot.

Therefore, the gas that is used for artificial ripening of green fruits is ethylene.