Degreening of citrus fruits can be achieved through –

✅Explanation:
Degreening is the process of removing the green chlorophyll pigment from the skin of citrus fruits to reveal their natural color. Ethylene is a plant hormone that plays a crucial role in fruit ripening, including the degreening of citrus fruits. When citrus fruits are exposed to ethylene gas, it triggers the breakdown of chlorophyll, allowing the underlying yellow or orange pigments to become visible.

📌Other Options Explanations:
(a) Gibberellic acid: This hormone is primarily involved in stem elongation and seed germination.
(b) Auxin: This hormone is involved in various plant growth processes, such as cell elongation and root development.
(d) Maleic Hydrazide: This is a plant growth regulator used to inhibit growth.