Which of the following is equipment with variable resistance?

The correct answer is resistance band because it provides variable resistance throughout its range of motion. As a user stretches a resistance band, the resistance increases; this means that the further you pull or stretch the band, the more difficult the exercise becomes. This feature is beneficial for strength training, as it can accommodate various fitness levels and allows for different levels of challenge depending on the individual's strength and flexibility.

In contrast, free weights offer a constant resistance throughout the movement, meaning the weight remains the same regardless of how the exercise is performed. Fixed machines also have a set level of resistance, allowing little variation. Medicine balls are solid weights that do not provide variable resistance; they maintain a constant mass regardless of how they are used. Overall, the unique property of resistance bands to change resistance based on the position and tension applied makes them the appropriate choice for equipment with variable resistance.