A, B & C drugs

What are class A B & C drugs? A are serious drugs B are average and c is okay.
What are so class A drugs?
Class A drugs are seriously harmful drugs.
Is it medical? 
No.
Who can take them if so?People who may be addicted or other habits which makes taking it Accor.
What types or drugs fit in to class A drugs? 
Herion cocaine and ecstasy LSD.
What types or drugs fit in to class B drugs?
These drugs are amphetamines such as speed and barbiturates & cannabis.