Which part of the gingiva is tightly bound to the underlying bone?

The attached gingiva is the correct answer because it is the portion of the gingiva that is firmly bound to the underlying alveolar bone. This attachment provides structural support and stability to the gums, ensuring that they remain closely associated with the underlying bone structure during various functions, such as chewing and speaking. The attached gingiva extends from the mucogingival junction to the base of the gingival sulcus, contributing to the overall health and function of the periodontium.

The marginal gingiva, also known as the free gingiva, is not attached to the bone but instead has a free edge that forms the gingival margin. The junctional gingiva is the area where the gingiva joins the tooth surface and is not directly bound to the bone. Understanding the distinctions between these different types of gingiva is crucial for recognizing their roles in periodontal health and disease.