In artificial ripening of banana, uncontrolled application of ethylene gas may cause over ripening of banana. It can be prevented from over-ripening by dipping in ascorbic acid solution.

Explanation:

Ascorbic Acid (Vitamin C) is the correct answer as it prevents the overripening of bananas and browning of cut fruits. Here's why:

1. Role of Ascorbic Acid:
- Ascorbic Acid is a powerful antioxidant that helps in preventing the oxidation of fruits and vegetables.
- It acts by neutralizing the free radicals and inhibiting the activity of enzymes like polyphenol oxidase and peroxidase, which are responsible for the browning of fruits and vegetables.

2. Preventing Overripening of Bananas:
- As bananas ripen, they produce ethylene gas, which triggers the ripening process.
- Over time, this ethylene gas concentration increases, leading to the overripening of bananas and the formation of brown spots on the skin.
- Ascorbic Acid helps in preventing the overripening of bananas by inhibiting the action of ethylene gas and delaying the ripening process.

3. Preventing Browning of Cut Fruits:
- When fruits or vegetables are cut or bruised, the damaged cells release enzymes like polyphenol oxidase.
- These enzymes react with oxygen in the air and cause browning or oxidation of the cut surfaces.
- Ascorbic Acid, being an antioxidant, prevents this browning by neutralizing the free radicals and inhibiting the activity of polyphenol oxidase.

4. Other Benefits of Ascorbic Acid:
- Apart from preventing browning and overripening, Ascorbic Acid also plays a crucial role in the synthesis of collagen, which is essential for maintaining healthy skin, gums, and blood vessels.
- It helps in boosting the immune system and acts as a scavenger for harmful free radicals in the body.
- Ascorbic Acid also enhances the absorption of iron from plant-based sources, preventing iron-deficiency anemia.

In conclusion, Ascorbic Acid (Vitamin C) is an important antioxidant that prevents the overripening of bananas and browning of cut fruits. It inhibits the action of enzymes responsible for these processes and neutralizes free radicals, thereby maintaining the freshness and appearance of fruits and vegetables.