Explanation:

- Water is composed of hydrogen and another element that bonds with it.

- The correct element that bonds with hydrogen to form water is oxygen.

- Oxygen combines with hydrogen in a 1:2 ratio to make H2O, commonly known as water.

- Option 2 - Oxygen is the correct answer.

Explanation of Options:

- Option 1: Carbon

- Carbon does not form water when combined with hydrogen.

- Carbon can combine with hydrogen to form hydrocarbons, like methane.

- Option 2: Oxygen

- Correct option, as explained above.

- Oxygen is essential in forming the water molecule, H2O.

- Option 3: Iodine

- Iodine reacts with hydrogen to form hydrogen iodide, not water.

- Option 4: Nitrogen

- Nitrogen combines with hydrogen to form ammonia (NH3), not water.