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
All of the following statements regarding Chlamydia are true, except: 
Select and explain. 
A. Gram positive, B. Trachoma, C. Causes Psittacosis, D. Causes Lymphogranuloma venerum
A: Gram positive
Answer: A: Gram positive 
Explanation: Chlamydia are gram negative, non motile, obligate intracellular parasites which multiply in the cytoplasm of host cells. Chlamydia trachomatis serotypes A, B and C cause trachoma, L1-3 serotypes cause lymphoganuloma venerum, D-K serotypes cause genital tract infection and conjunctivitis. Pscittacosis is caused by Chlamydia psittaci.