$A -$ Thyroid gland secretes a protein hormone called thyrocalcitonin $(TCT)$,which regulates the blood calcium levels.
$R - TCT$ is a hypercalcemic hormone.

• A
  $A$ and $R$ both are correct.
• B
  $A$ and $R$ both are incorrect.
• C
  $A$ is correct and $R$ is incorrect.
• D
  $A$ is incorrect and $R$ is correct.