What is the most accurate definition of the incubation period (of an infectious disease) ?

A) The time of onset of clinical illness or the onset of recognizable symptoms
B) The interval from receipt of infection to the time of onset of clinical illness (the onset of recognizable symptoms)
C) The time of invasion by an infectious agent
D) The time between initiation of infection and first shedding or excretion of the agent
E) The period between exposure and the onset of infectiousness

The incubation period is defined as the interval from receipt of infection to the time of onset of clinical illness (the onset of recognizable symptoms); in other words,the time between the moment of developing symptoms and the moment of invasion by an infectious agent."The time of onset of clinical illness or the onset of recognizable symptoms" is not true as it corresponds to "time of onset." "The time of invasion by an infectious agent" is not true as it corresponds to "time of infection." "The time between initiation of infection and first shedding or excretion of the agent" and "The period between exposure and the onset of infectiousness" are not true as they correspond to the latent period.(The latent period is focusing on the onset of infectiousness,but the incubation period is focusing on the onset of the symptom.)