The correct answer is option 4: Water and Oxygen.

Photosynthesis is the process by which green plants convert sunlight, carbon dioxide, and water into glucose (carbohydrate) and oxygen. During photosynthesis, plants absorb carbon dioxide from the atmosphere along with water from the roots. These two components are then used in the process to produce glucose (carbohydrate) and oxygen.

Option 1: Carbon dioxide only - This is not correct because carbon dioxide is not the only product of photosynthesis. It is one of the reactants that is consumed during the process.

Option 2: Oxygen only - This is not correct because while oxygen is a product of photosynthesis, it is not the only product. Green plants produce both glucose and oxygen as a result of photosynthesis.

Option 3: Water and Carbon dioxide - This is not correct because water and carbon dioxide are the reactants of photosynthesis, not the products.

In conclusion, option 4 - Water and Oxygen, is the correct answer as water and oxygen are the byproducts of photosynthesis along with glucose (carbohydrate).