Answer:
The correct option is c: 1.5 cm.
Explanation:
The amplitude of the motion can be calculated using the following equation:

Where:
A: is the amplitude
v: is the speed = 15 cm/s
ω: is the angular speed
First, we need to find the angular speed:

Where:
T is the period = 628 ms

Now we can find the amplitude:

Therefore, the correct option is c: 1.5 cm.
I hope it helps you!