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
The most sensitive investigation for the diagnosis of asymptomatic Chlamydial infection is: 
Select and explain. 
A. Ligase Chain Reaction, B. Serodiagnosis, C. Iodine Staining, D. Culture
A: Ligase Chain Reaction
Answer: A: Ligase Chain Reaction 
Explanation: Ligase chain reaction (LCR) or polymerase chain reaction (PCR) are the most sensitive NAA methods. Isolation of C trachomatis has been the gold standard for diagnosis, but it is clear that it is less sensitive than specific nucleic acid amplification (NAA) assays. Culture is usually performed using idoxuridine or cycloheximide treated McCoy cells. C trachomatis inclusions contain glycogen and are stainable with iodine Serodiagnosis not helpful for most genital infections. Detection of IgM antibodies against C trachomatis is helpful in cases of infant pneumonitis. Ref: Ray C.G., Ryan K.J. (2010). Chapter 39. Chlamydia. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.