Assertion: A particle is projected with speed `u` at an angle `theta` with the horizontal. At any time during motion, speed of particle is `v` at angle `alpha` with the vertical, then `v sin alpha` is always constant throughout the motion.
Reason: In case of projectile motion, magnitude of radial acceleration at topmost point is minimum.
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.