The correct answer is option 4: -1 m/s².

To calculate average acceleration, we need to determine the change in velocity and the time interval. In this case, the time interval is from 8 seconds to 12 seconds. By examining the graph, we can see that from 8s to 12s, there is a decrease in velocity, indicating negative acceleration.

The average acceleration formula is given by:

Average Acceleration = (Change in Velocity) / (Time Interval)

From 8s to 12s, the change in velocity can be determined by subtracting the final velocity at 12s from the initial velocity at 8s. Since the velocity decreases from 10 m/s to -2 m/s, the change in velocity is -2 m/s - 10 m/s = -12 m/s.

The time interval is given as 12s - 8s = 4s.

Plugging in the values into the formula:

Average Acceleration = (-12 m/s) / (4 s) = -3 m/s².

Therefore, the value of average acceleration from 8s to 12s is -3 m/s².

Alert - correct answer should be -3 m/s².