Photosynthesis and its Products
Photosynthesis is the process by which green plants, algae, and some bacteria convert sunlight, water, and carbon dioxide into glucose (a sugar) and oxygen. It is a vital process that plays a significant role in the Earth's ecosystem as it produces oxygen, which is essential for the survival of most organisms.

Products of Photosynthesis
During photosynthesis, plants produce several important products. Let's discuss each of them:

1. Oxygen (O2): The most significant product of photosynthesis is oxygen. Plants release oxygen into the atmosphere as a byproduct of photosynthesis. This oxygen is then utilized by animals, including humans, for respiration. Oxygen is crucial for the survival of aerobic organisms as it is required for the production of energy through cellular respiration.

2. Glucose (C6H12O6): Glucose is a simple sugar that is produced during photosynthesis. It is the primary source of energy for plants and is used for various metabolic processes. Plants store excess glucose in the form of starch for later use. Glucose is also a vital source of energy for animals and humans who consume plants or plant-based products.

3. Carbon Dioxide (CO2): Carbon dioxide is not a product of photosynthesis but rather a reactant. It is absorbed by plants from the atmosphere through tiny openings called stomata on their leaves. Carbon dioxide is essential for photosynthesis as it provides carbon atoms that are used to build glucose molecules.

Correct Answer
The correct answer is (a) Carbon dioxide. Carbon dioxide is not a product of photosynthesis but rather a reactant. It is consumed during photosynthesis to produce glucose and oxygen. The other options, glucose and oxygen, are indeed products of photosynthesis.

In summary, photosynthesis is a vital process that produces oxygen and glucose. Carbon dioxide is used as a reactant during photosynthesis, and it is not a product of this process.

Answer ' B ' is correct