Which of the following statements is inappropriate?

• A
  The majority of mammals,including human beings,form two sets of teeth during their life: a set of temporary milk or deciduous teeth and a set of permanent or adult teeth.
• B
  The oral cavity leads into the pharynx,which serves as a common passage for food and air.
• C
  Each tooth is embedded in a socket of the jawbone. This type of attachment is called diphyodont.
• D
  The hard chewing surface of the teeth is made up of enamel.