Which of the following is the best example of a core exercise?

The best example of a core exercise is a plank. This exercise is specifically designed to engage and strengthen the core muscles, which include the abdominals, obliques, and lower back. The plank requires stabilization of the body in a horizontal position, demanding that these core muscles work to maintain posture without sagging or arching.

In contrast, while battle ropes, lunges, and sledgehammer exercises can contribute to overall fitness and may engage core muscles to some extent, they are not primarily focused on core stabilization. Battle ropes tend to emphasize cardiovascular endurance and upper body strength, lunges primarily target the lower body, and sledgehammer exercises involve dynamic, powerful movements that engage multiple muscle groups but do not isolate the core in the manner that a plank does. Thus, the plank is specifically recognized as a core exercise due to its targeted focus on core engagement and stabilization.