The correct option is B February
The revolution of the earth around the sun takes approximately 365 days and 6 hours. We ignore the 6 hours for our convenience. Once every four years, these 6 hours are added to make one day. This extra day is added to the month of February which has the fewest number of days. Thus, every fourth year, February has 29 days instead of 28 days. Such a year with 366 days is called leap year.