__ 17. One way that bacteria and fungi are important to the environment is that they a. produce oxygen. b. use the sun's energy to make their own food. c. are a major food source in many ecosystems. d. break down dead organisms.

## Step 1<br />This question is about the role of bacteria and fungi in the environment. Each of the options provided represents a different function that various organisms can perform in an ecosystem.<br /><br />## Step 2<br />Option a. suggests that bacteria and fungi produce oxygen. While it is true that certain types of bacteria, such as cyanobacteria, are known as oxygenic phototrophs and produce oxygen, not all bacteria and fungi have this ability.<br /><br />## Step 3<br />Option b. suggests that bacteria and fungi use the sun's energy to make their own food. This is a characteristic of autotrophs, which includes plants and some bacteria, but not fungi.<br /><br />## Step 4<br />Option c. suggests that bacteria and fungi are a major food source in many ecosystems. While some animals do consume bacteria and fungi, they are not the primary food source in most ecosystems.<br /><br />## Step 5<br />Option d. suggests that bacteria and fungi break down dead organisms. This is a key role of bacteria and fungi in the environment, as they are decomposers. They break down dead organisms and waste products, recycling nutrients back into the ecosystem.