Answer: A). Energy is needed to start photosynthesis and is a product of cellular respiration.
Step-by-step explanation:
Energy in the form of sunlight is absorbed by the plants so as to prepare their food (carbohydrates)in the process of photosynthesis.
The energy is produced in the process of cellular respiration. The cellular respiration involves the break down of glucose molecules in the food in the form of energy currencies called as ATP (Adenosine triphosphate) molecules. This form of energy is required for regulating cellular metabolism and vital functions.