Consider the following statements regarding digestion and absorption in mammals. Identify whether they are true or false and select the correct option accordingly.
$I.$ Both Kupffer's cells and Glisson's capsule are characteristics of the mammalian liver.
$II.$ In dentition,thecodont means that teeth are embedded in the socket of jaw bones.
$III.$ There are three pairs of salivary glands in human beings; out of them,the parotid,situated beneath the tongue,is the smallest salivary gland.
$IV.$ Zymogens (inactive forms of enzymes) are not the secretions of peptic cells.

• A
  All statements are true.
• B
  All statements are false.
• C
  $I$ and $II$ are true while $III$ and $IV$ are false.
• D
  $III$ and $IV$ are true while $I$ and $II$ are false.