Final answer:
For playing volleyball, the essential equipment needed is a net and a ball, as they are necessary to play the game according to the official rules.
Step-by-step explanation:
For playing volleyball in a physical education class, the essential equipment needed consists of a net and a ball. These basic items are required to play the game following the official rules, including getting the ball over the net and preventing it from touching the ground on your side.
The activity focuses on teamwork and coordination, allowing multiple players to participate simultaneously, making it an ideal game for school settings. While not specifically mentioned in the list of equipment, participants often wear appropriate athletic clothing and shoes for safety and performance. The correct option from the given choices would be 'c. a net, a ball', as these are the necessary items to play the game.