This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunomodulators, Subject name: Pharmacology
All are true about levamisole EXCEPT: 
Select and explain. 
A. Act as an immunostimulator, B. Act as an immunodepressor in high doses, C. Single dose is sufficient for the treatment of psoriasis, D. Acts antihelminthic by causing depolarization
C: Single dose is sufficient for the treatment of psoriasis
Answer: C: Single dose is sufficient for the treatment of psoriasis 
Explanation: Levamisole- Active against many nematodes, but use is restricted to ascariasis and ancylostomiasis because the action on other worms is poor. The ganglia in worms are stimulated causing tonic paralysis and expulsion of live worms. Interference with carbohydrate metabolism (inhibition of fumarate reductase)may also contribute. It is an immunostimulant, used for slow spreading vitiligo to be used for at least 6 weeks ESSENTIALs of MEDICAL PHARMACOLOGY SIXTH EDITION -KD TRIPATHI Page 812