The rate at which distance is covered is called
a. speed
b. velocity
c. acceleration
d. displacement

Option A, speed

Explanation:

The rate at wich distance is covered is also the rate at wich the position changes, for example, if you cover 4 meters in 1 second, this rate is 4m/s, this is speed.

Velocity is when speed has also a direction, for example, 4m/s to south, this is a vector.

acceleration is the rate of change of the velocity.

Displacement is the change in position over a period of time.

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.

i believe the answer is a