A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of earth [IIT 1998]

• A. The acceleration of S is always directed towards the centre of the earth
• B.             The angular momentum of S about the centre of the earth changes in direction but its magnitude remains constant
• C.             The total mechanical energy of S varies periodically with time
• D.             The linear momentum of S remains constant in magnitude