Why do plants make their own food? (I tried googling it and all I could find was how they make it, not necessarily why)

They take the carbon dioxide, water and sunlight they take in from their leaves to make food

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.