Comets mover around the sun in highly elliptical orbits. The gravitational force on the comet due to the sun is not normal to the comet s velocity in general. Yet the work done by the gravitational force over every orbit of the comet is zero. Why?

• A. The gravitational force is conservative, hence work done is zero
• B. The gravitational force is non-conservative, hence work done is zero
• C. Energy is absent, hence work done is zero
• D. Force is in negative direction