(a) The alimentary canal stretches from the buccal cavity to the anus.

buccal cavity is the starting point of alimentary canal, while it terminates at anus.

(b) Teeth are rooted in separate sockets in between the gums.

human teeth are thecodont, i.e. they are fitted into a socket.

(c) Digestion of food starts in the buccal cavity and gets completed in the small intestine.

buccal cavity initiates the process of digestion by partially digesting starch. While in small intestine the process of digestion gets completed. Large intestine is not involved in digestion process, it only absorbs water form undigested food.

(d) Liver is the largest gland in the human body.

liver is the largest gland in human body which helps in various life processes.