Which of the following statements are not correct?
$a$) Antihistamine also functions as an antacid
$b$) The shape of an active site of an enzyme does not change when the drug binds to an allosteric site
$c$) Chemical messengers communicate the message between two neurons
$d$) Potassium soaps are hard,while sodium soaps are soft to skin
The correct answer is

• A
  $a, b, d$
• B
  $b, c, d$
• C
  $a, c$
• D
  $c, d$