Assertion: The range of a projectile is maximum at 45°.
Reason: At `theta = 45°`, the value of `sin theta` is maximum.
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.