The byproduct of photosynthesis is

nitrogen
water
oxygen
carbon dioxide

Option (3)

Explanation:

The photosynthesis refers to the process by which the green plants can prepare their own food in the presence of sunlight, water, and carbon dioxide, and in turn, it liberates oxygen. These plants are called autotrophs or producers.

This green plants are the major producers of oxygen and helps in the reduction of carbon dioxide from the atmosphere.

The equation that shows the process of photosynthesis is given below-

6CO₂ + 6H₂0 + (sunlight/energy) → C₆H₁₂O₆ + 6O₂

Thus, the byproduct of the photosynthesis process is Oxygen (O₂)

Hence, the correct answer is option (3).