Those trees have (fewer, less) fruit on them.

I'll be glad to check your answer.

In this case, the correct word to use is "fewer." "Fewer" is used when you are referring to a countable noun, such as individual fruit. Since you can count the number of fruit on the trees, you should use "fewer."

To determine whether to use "fewer" or "less," you can follow these general rules:
- Use "fewer" when referring to countable items or individual units.
- Use "less" when referring to uncountable nouns or quantities.

Here's an example to illustrate the difference:
- "There are fewer apples in the basket." (countable noun: individual apples)
- "There is less water in the glass." (uncountable noun: water, which cannot be counted as individual units)

Remember, using the correct word helps to communicate your message accurately.