Question

what is the meaning of one rotten apple spoils the whole barrel?
people will act badly when they are not being
watched
a bad person can make a group do bad things
watch out for people who might cheat you

Explanation:

The phrase "one rotten apple spoils the whole barrel" is an idiom. It means that a bad person can have a negative impact on a group, causing the group to do bad things. This is a common expression used in language to convey the idea of a single negative element affecting the entire group.

Answer:

a bad person can make a group do bad things