This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infectious Disease Epidemiology, Subject name: Social & Preventive Medicine
The interval between the primary and the secondary case is called as: 
Select and explain. 
A. Serial interval, B. Generation time, C. Median Incubation period, D. Latent period
A: Serial interval
Answer: A: Serial interval 
Explanation: Ref: 21st edition Park. Pg 95Explanation:Incubation periodBetween invasion by an infectious agent and appearance of the first sign / symptomsMedian Incubation periodThe time required for 50 percent of the cases to occur following exposureLatent periodEqual to IP in non-communicable diseaseSerial intervalBetween onset of primary case and secondary caseGeneration timeInterval between the receipt of infection by a host and maximal infectivityPeriod of communicabilityDuring which an infectious agent can be communicated