Which of the following is an illegal hold in high school wrestling?

The headlock with neck cranking is considered an illegal hold in high school wrestling due to the potential for serious injury. This type of maneuver can place excessive torque on the neck and spine of the opponent, leading to risk of severe injury. High school wrestling rules place a strong emphasis on the safety of the competitors, and maneuvers that are deemed to put undue stress on vulnerable areas of the body, such as the neck, are prohibited.

In contrast, the body lock, half Nelson, and single-leg takedown are all legal techniques that are widely used in wrestling. The body lock is a common grip used to control an opponent, the half Nelson is a method utilized in both top and neutral positions to secure control, and the single-leg takedown is a fundamental technique for bringing an opponent to the mat. None of these moves carry the same level of risk of injury as the headlock with neck cranking, hence their legality in the sport.