Which hairstyle is acceptable without a hair cover as long as the hair-length rule has been met?

The correct choice is dreadlocks, as they can be considered an acceptable hairstyle without the need for a hair cover, provided that they adhere to the hair-length rule established in wrestling regulations. This rule typically requires that hair not extend beyond certain lengths for safety and to maintain a competitive standard. Dreadlocks, when styled appropriately, can be kept under this length rule and do not pose any risks for entanglement or injury during matches.

In contrast, long straight hair may exceed the hair-length limit set by wrestling guidelines, potentially necessitating a hair cover to ensure compliance with regulations. A buzz cut is a very short hairstyle that generally falls well within the length requirements, but it does not showcase the same cultural significance and purpose as dreadlocks. The mohawk style, depending on its height and design, could also violate hair-length standards and thus requires a hair cover to adhere to safety protocols. Therefore, dreadlocks are uniquely positioned as a culturally significant hairstyle that remains compliant with the necessary wrestling guidelines.