Final answer:
The question relates to sports like tennis, badminton, or table tennis, where the opponent returns the serve immediately after it has been hit.
Step-by-step explanation:
The question, 'Which opponent can return right after it is served?' is most likely referring to a sport such as tennis, badminton, or table tennis (ping-pong), where players take turns serving the ball or shuttlecock to each other.
In these sports, the opponent is expected to return the serve immediately after it has been delivered, following the specific rules of the sport governing how a serve must be made and returned.
For example, in tennis, the opponent must return the ball before it bounces twice on their side of the court, and in badminton, the shuttlecock must be hit before it touches the ground.