Me
if all the grass disappeared from this community, which change would be
most likely to occur?

The letter A is the right answer.

Explanation:

As you can see from the diagram above, grass is one of the deer's main food and survival sources. If all the grass in this ecosystem were to disappear, the deer would be a very affected organism and that would cause its population to decrease, it just wouldn't cause its total extinction because the deer has two other sources of food.

The decrease in the deer population would affect the entire food chain to which it belongs and could harm other animals such as coyotes and cougar.