Which of the following sentences is an example of active voice?

The sentence "John threw the ball" is an example of active voice because the subject of the sentence, "John," performs the action of the verb, which is "threw." In active voice constructions, the focus is on the subject completing the action, making the sentence direct and clear. This structure generally leads to more vigorous and dynamic writing.

In contrast, the other sentences illustrate passive voice, where the subject is acted upon by the verb. For instance, "The ball was thrown by John" shifts the focus from John to the ball, emphasizing the action received rather than who performed it. Similarly, "The ball was caught by the player" and "The player was seen catching the ball" also place emphasis on the action’s recipient rather than the doer, making the sentences less direct. Therefore, option B is the only construction that maintains an active voice, clearly establishing John as the doer of the action.