The correct option is B Revolution
The time taken for a planet to orbit around the Sun is defined as a revolution. It takes roughly 365 days for Earth to complete this revolution. This is what our calendar year is based on. The Gregorian calendar is based on the revolution of Earth around the sun to be 365.2425 days in length. The inclusion of a "leap year", one where we have an extra day, happens every four years to account for the 0.2425.