Explanation:

- A lot on one’s plate: This idiom refers to having many tasks or responsibilities to handle, suggesting a busy or overwhelmed state.

- Option 1: To eat a lot

- Incorrect. This does not relate to the idiom’s intended meaning about workload or responsibilities.

- Option 2: A lot to do

- Correct meaning. When someone has "a lot on their plate," they have many responsibilities or tasks.

- Option 3: To have a serious ailment

- Incorrect. This does not capture the idea of having many tasks or responsibilities.

- Option 4: To serve all dishes on one plate

- Incorrect. This is more literal and doesn't convey the idiom's metaphorical sense of being busy.