This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Chinese letter arrangement is seen in: March 2009 & 2011 
Select and explain. 
A. M.tuberculosis, B. Corynebnacterium diphtheria, C. Chlamydia trachomatis, D. M. leprae
B: Corynebnacterium diphtheria
Answer: B: Corynebnacterium diphtheria 
Explanation: Ans. B: Corynebnacterium diphtheria Nonpathogens that resemble Corynebacterium diptheriae in appearance are termed "diptheroids". The arrangement of the bacteria provide a clue to distinguish the pathogen Corynebacterium diptheriae from the nonpathogenic diptheroids. C. diptheriae bacteria form 90 degree angles to one another, forming "X's", "Y's", or "Chinese letters". In contrast, diptheroids are often in parallel arrangements called "palisades". The diagnostic significance of metachromatic granules arises from the fact that the causative agent of diptheria, Corynebacterium diptheriae, characteristically produces metachromatic granules.