Which situation has a result of 0?

A) Tim walks 2.3 miles due east and turns around and walks 2.3 miles due west. How far did Tim walk?
B) Mike is 7 years younger than his brother. In 7 years, what will be the age difference between Mike and his brother?
C) Dion opens a checking account and deposits $24.75. He then withdraws $24.75. How much money is left in the checking account?
D) Art is in a hot -air balloon 230 feet off the ground. The balloon climbs another 230 feet. How high off the ground is the hot-air balloon?