The leaves of a plant first prepare food A by photosynthesis. Food A then gets converted into food B. What are A and B?

Photosynthesis is a process in which green plants use sunlight to make their own food. Photosynthesis requires sunlight, chlorophyll, water, and carbon dioxide gas. The reaction involved in photosynthesis is:

The glucose formed in the above reaction is converted into starch and then is used by the plant for supplying energy to the plants.

Hence here A is Glucose and B is starch.