Correct Answer: Mistreat someone in the same way they have treated others

Solution : The right choice is the second option.

The idiom "give someone a taste of their own medicine" is a figurative expression that suggests treating someone in the same way they have treated others, especially if the treatment was negative or harmful. It implies a form of retaliation or retribution to make the person realise the impact of their actions by experiencing it themselves.

Therefore, the correct answer is, mistreat someone in the same way they have treated others.