What is the sidereal period used in Kepler's third law?
A. the time taken by the planet for one rotation around its axis
B. the time it takes for a planet to complete one orbit with respect to the background of fixed stars
C. the orbital period of a planet as it revolves around the Sun as observed from Earth
D. the time taken by the planet to transition from day to night
E. the time taken by the planet to travel from the aphelion to the perihelion