Assertion: If a moving charged particle enters into a region of magnetic field from outside, it does not complete a circular path.
Reason: Power associated with the force exerted by a magnetic field on a moving charged particle is always equal to unity.
Options:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.