The presence of which structure allows teeth to feel pain?

The correct choice is based on the role of dentine in the sensory function of teeth. Dentine contains microscopic tubules filled with fluid and are connected to nerve endings. When the dentine is exposed, such as when enamel is worn down or when there are cavities, stimuli like hot, cold, or sweet substances can cause the fluid in these tubules to move. This movement can stimulate the nerve endings, leading to the sensation of pain.

Cementum, although important for anchoring the tooth to the periodontal ligament, does not contain nerve endings capable of sensing pain. The amelodentinal junction is the interface between enamel and dentine but does not itself provide sensory function. Enamel, while crucial for protecting the tooth structure, is primarily a non-living tissue and does not contain any nerves or sensory components. Therefore, the sensation of pain is due to the properties and structure of the dentine, making it the answer to the question.