Final answer:
To find the average velocity, one must know the net displacement and the time interval; if the net displacement is 0 m, then the average velocity would be 0 m/s regardless of the average speed provided because velocity is dependent on displacement. Option A is correct.
Step-by-step explanation:
The average velocity of an object is the total displacement divided by the time over which the displacement occurred. Without additional information about displacement, we cannot determine the average velocity simply based on the given average velocity value of 20 m/s or the total distance and average velocity information provided.
However, based on the other pieces of related information provided, we can infer that if the net displacement of an object is 0 m, then the average velocity would also be 0 m/s, since velocity is a vector quantity that depends on displacement, not just distance covered.
The average velocity of an object can be calculated by dividing the total displacement by the time taken. In this case, we have a net displacement of 0 m and a total time of 4 s. Therefore, the average velocity during the first 4 seconds would be 0 m/s.