All the following statements are correct for $Bt$ toxin,but one is wrong. Which one is wrong?

• A
  $Bt$ toxin is produced by bacteria called $Bacillus$ $thuringiensis$.
• B
  $Bt$ toxins are protein toxins like thurioside and sporeine which are active against different groups of insects.
• C
  $Bt$ toxin is harmful for man.
• D
  Upon ingestion by susceptible insects,the $Bt$ protoxin is converted into an active form and kills the insects.