Which of the following idioms is NOT used correctly?

A. Thank you for the hundred dollar gift, but I need $100,000. One hundred dollars is just “a drop in the bucket” compared to what I need.

B. I decided not to pay $300 for an iPhone. “A penny saved is a penny earned.”

C. I can’t believe that he only got a year in jail for committing that bank robbery. I guess “a leopard can’t change its spots.”

D. I’m glad his boss yelled at him in the same way that he yells at us. It’s great to see him “get a taste of his own medicine.”