A

Step 1: Let's analyze the forces acting on the block on the inclined plane.
Step 2: The block has an applied force F directed up the incline to move it with velocity v of 3 m/s.
Step 3: As the block moves up the incline with a constant velocity, the friction must act in the opposite direction to the motion. Here, the motion is upwards, so the friction force must act down the incline.
Step 4: The nature of friction is opposing the direction of applied force. Since the block is sliding upward and experiencing the influence of gravity pulling it downwards, the friction must also act downwards to oppose the upward movement.
Conclusion: Therefore, the direction of friction on the block is down the incline, and the nature is kinetic friction as the block is already in motion. Hence, the correct answer is A.