Which of the following statements is not true?

• A
  $Erythromycin$ is a bacteriostatic antibiotic.
• B
  $Ampicillin$ is not a natural antibiotic.
• C
  $Prontosil$ is not converted into $sulphanilamide$ in the body.
• D
  $Vancomycin$ is a broad spectrum antibiotic.