Upper molars in human dentition have

Human teeth are:
$(1)$ Of different types.
$(2)$ Embedded in a socket of the jaw bone.
$(3)$ Formed in two sets during their life.
This type of dentition is called:

Identify the parts $A$ and $B$ from the given cross-sectional diagram of the alimentary canal.

Match the following columns:

Column-$I$	Column-$II$
$P$. Thecodont	$I$. Human possesses four types of teeth
$Q$. Diphyodont	$II$. Permanent teeth replace milk teeth
$R$. Heterodont	$III$. Human teeth are embedded in the jaw bone

The pulp cavity of teeth is lined by

Describe the pharynx,oesophagus,and external structure of the stomach in the human digestive tract.