Here's why:

* Plants use a process called photosynthesis to convert sunlight, water, and carbon dioxide into energy (in the form of sugar) and oxygen. This is how they make their own food.

* Animals cannot make their own food and must eat plants or other animals to obtain energy.

* Fungi are decomposers and obtain energy by breaking down dead organisms.

* Bacteria are a diverse group, with some being able to produce their own food, while others rely on other sources of energy.

Let me know if you have any other questions!