<prompt> Generation time in epidemiology is defined as ?The interval between marriage and the bih of first childThe interval of time between the receipt of infection by host and maximal infectivity of the hostThe interval of time between primary case and secondary casesInterval of time between invasion by infectious agent and appearance of first sign or symptom of the disease in question  <response>: Ans. is b i.e., Interval of time between receipt of infection by the host and maximal infectivity of the host 