The answer is A, dentine. Dentine is the hard, yellowish-white tissue that makes up the bulk of a tooth. It is located beneath the enamel and cementum, and it contains the pulp chamber, which contains the nerves and blood vessels of the tooth. Incisors, canines, premolars, and molars are all types of teeth. Incisors are the eight front teeth, which are used for cutting food. Canines are the four pointed teeth next to the incisors, which are used for tearing food. Premolars are the eight teeth behind the canines, which are used for crushing and grinding food. Molars are the twelve teeth at the back of the mouth, which are used for grinding food.
Dentine is different from the other options because it is not a type of tooth. It is a type of tissue that makes up the bulk of a tooth.