ANSWER:
5th option: 80 m/s²
Explanation:
Given:
Amplitude (A) = 20 cm = 0.2 m
speed in the equilibrium position (v) = 4m/s
To calculate the acceleration, the first thing is to calculate the frequency, using the following formula (maximum speed, i.e. the speed in the equilibrium position):

Now, we calculate the value of the maximum acceleration using the following formula:

Therefore, the maximum acceleration of the system is equal to 80 m/s² so the correct answer is 5th option: 80 m/s²