The correct option is A Both assertion and reason are correct
Photosynthesis is a process by which plants synthesise their own food with the help of sunlight and chlorophyll and releasing oxygen back into the atmosphere. Many organisms feed on plants while others are preyed upon by different organisms. Ultimately, all life forms depend directly or indirectly on sunlight for their energy requirements. Hence, the assertion is correct.
During photosynthesis, plants consume carbon dioxide and water and convert these reactants into glucose and oxygen with the help of sunlight and chlorophyll. Glucose is either utilised by plants or stored as starch for later use. However, oxygen is released into the atmosphere which is crucial for most living organisms. As stated earlier, plants are fed upon by other animals too. Hence, reason is also a valid explanation.
Carbon dioxide + Water Sunlight−−−−−−→Chlorophyll Glucose + Oxygen