Crypts of Lieberkuhn are present in

The diagram given below depicts the human digestive system. Label it from $A$ to $F$ and choose the correct option accordingly.

Identify the location and function of the following:
$(1)$ Villi
$(2)$ Oxyntic cells

Which of the following are found in the portal area of the liver?
$i$. Branch of hepatic portal vein
$ii$. Branch of hepatic vein
$iii$. Branch of bile duct
$iv$. Branch of hepatic artery
Select the correct option -

The water content in enamel is approximately .......

Crypts of Lieberkühn are found in: