Which gland is primarily associated with secretion in the posterior part of the tongue?

The gland primarily associated with secretion in the posterior part of the tongue is Von Ebner's glands. These serous glands are located beneath the circumvallate papillae at the back of the tongue and are specifically responsible for the secretion of digestive enzymes, which play a role in the initial stages of digestion. The secretions from Von Ebner's glands also help to wash away food particles, allowing taste receptors to function more effectively.

While the other glands listed also play important roles in saliva secretion, they are not specifically localized to the posterior part of the tongue. The submandibular and sublingual glands, for instance, are primarily responsible for mucous secretions in the submandibular and sublingual regions of the oral cavity, and the parotid gland primarily secretes saliva into the mouth around the upper molars. Thus, Von Ebner's glands are uniquely positioned to serve the posterior region of the tongue effectively.