<prompt> Clostridium botulinum toxin mode of action is by: March 2012Presynaptic blockPostsvnaptic blockCompetitive inhibition of acetylcholineDestruction of acetylcholine  <response>: Ans: A i.e. Presynaptic block Cl. Botulinum toxin acts by blocking the production release of acetylcholine at the synapses neuromuscular junctions 