This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
Which non-diphtheria corynebacterium is used as immunomodulator? 
Select and explain. 
A. C. diphtheriae, B. C. parvum, C. C.hofmanni, D. C.pseudotuberculosis
B: C. parvum
Answer: B: C. parvum 
Explanation: Ans. is 'b' i.e., C. parvumThe immunomodulator Corynebacterium parvum stimulates the reticuloendothelial system and causes splenic hypertrophy. The ability of C parvum to stimulate splenic regeneration in hemisplenectomized mice and decrease susceptibility to intranasal pneumococcal challenge was studied.