(A)   comets move around the Sun in elliptical orbits.   The gravitational  force acting on the comet due to Sun is not normal to the comets velocity but the work done by the gravitational force over every complete orbit of the comet is zero.
( R) Gravitational Force is a non conservative force.

• A

  Both A & R are true and R is the correct explanation of  ‘A’

• B

  Both A and R are true and R not the correct explanation of ‘A’

• C

  A is true and ‘R’ is false.

• D

  A is false and ‘R’ is true.