The correct answer is (d). Ethylene and Acetylene are the gases used for artificial ripening of fruits.
Ethylene is a plant hormone that is responsible for the ripening of fruits. It is produced naturally by fruits as they ripen, and it can also be artificially produced in a laboratory. Ethylene is used to ripen fruits that are not ripe enough to be eaten, or to ripen fruits that have been stored for a long time.
Acetylene is a gas that is produced when ethylene is heated. It is also a plant hormone, and it has a similar effect to ethylene on the ripening of fruits. Acetylene is often used in combination with ethylene to ripen fruits more quickly.
Ammonia and carbon dioxide are not used for artificial ripening of fruits. Ammonia is a gas that is used in fertilizers and cleaning products. Carbon dioxide is a gas that is used in fire extinguishers and carbonated beverages.