Photosynthesis can be described as a process by which organisms like plant and some algae make their own food. They use light energy from the sun to convert carbon dioxide and water into glucose and oxygen. Oxygen is the by- product of this reaction. Hence, option A is correct.
Other options are wrong because photosynthesis is not a process by which energy can be extracted from food or it is not a process by which excretion of waste occurs. Neither is it a process of reproduction.
The engulfed object is thus enclosed within a membrane-bound vacuole called a phagosome. The phagocyte digests the ingested particle with hydrolytic enzymes, which are contained within membrane-enclosed sacs called lysosomes found within the cell.
