Final answer:
The correct velocity of the sedan after acceleration and setting cruise control to 20 m/s is A. The velocity of the sedan is 20 m/s because the cruise control maintains that constant velocity.
Step-by-step explanation:
The answer to the question of what the velocity of the sedan could be, after it has accelerated from 0 m/s to 20 m/s and its cruise control was set to 20 m/s, is A. The velocity of the sedan is 20 m/s. This is because once the sedan reaches 20 m/s and the cruise control is activated, the vehicle is designed to maintain that constant velocity until acted on by another force or until the cruise control setting is changed. Therefore, options B, C, and D are incorrect as they either represent the car at rest, moving at a slower velocity than it accelerated to, or exceeding the cruise-controlled velocity without mentioning any further acceleration.