Crypts of Lieberkuhn are present throughout the

The gallbladder is located in the:

Which of the four layers of the wall of the alimentary canal shows the most variation?

Rugae are present in the wall of . . . . . . .

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 -

This vitamin is also known as "Castle's extrinsic factor".