In this question, Assertion (A) states that if a person in an elevator that is going up at a constant velocity drops a coin, then the coin will fall with uniform velocity. Reason (R) states that the elevator is not moving with any acceleration or retardation.

Option 1 states that both A and R are individually true and R is the correct explanation of A.

Regarding Assertion (A), it is true that if the elevator is going up at a constant velocity, the coin will fall with uniform velocity. This is because the coin and the person in the elevator are both subject to the same gravitational force, which causes objects to fall with a constant acceleration (9.8 m/s^2).

Regarding Reason (R), it is also true that if the elevator is not moving with any acceleration or retardation (which means it is moving at a constant velocity), the coin will fall with a constant velocity. This is because there is no force acting on the coin in the horizontal direction, so it will only experience the force of gravity pulling it downward.

Therefore, Option 1 is the correct answer as both Assertion (A) and Reason (R) are individually true and Reason (R) is the correct explanation of Assertion (A).