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: Medicine
Which of the following is not true about Nosocomial infection? 
Select and explain. 
A. May also be present at the time of admission, B. Presents within the period of hospital admission, C. May also develop symptoms after discharge from hospital, D. It is unrelated to the primary illness of the patient
A: May also be present at the time of admission
Answer: A: May also be present at the time of admission 
Explanation: Nosocomial infection occurs only after hospital admission, and are neither present nor incubating at the time of patient's admission. Most nosocomial infections become clinically apparent during hospitalization whereas those with long incubation period or with long latency may become apparent after hospital discharge.