Answer:
A. in the cells of autotrophs
Step-by-step explanation:
Photosynthesis takes place in the cells of autotrophs. Autotrophs are capable of manufacturing their own food by two major means which is by photosynthesis or by chemosynthesis. 
- In photosynthesis green plants manufacture their foods using sunlight to synthesize energy rich compounds from carbon dioxide and water. 
 - The product is often times glucose and oxygen gas. 
 
Heterotrophs on the other hand depends on the food manufactured by the autotrophs for their nourishment