You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Regarding point source epidemic, false statement (s) is/are:a) Rapid rise & fallb) Only infectious disease can causec) Explosived) Cases occur even after incubation periode) No secondary wave and explain in detail?
Features of point source (single exposure) epidemics 

The exposure to the disease agent is brief and essentially simultaneous → single exposure.
Because disease agent enters into all exposed persons at same time → the resultant cases all develop within one incubation period of the disease.
The epidemic curve rises and falls rapidly.
Because exposure is single (simultaneous) with no further exposure → No secondary wave (no secondary case).
Epidemic tends to be explosive, there is clustering of cases within a narrow interval of time.
Point source epidemics are mostly (not always) due to exposure to an infectious agent.
Examples → Food poisoning, Bhopal gas tragedy, Minamata disease in Japan, Chernobyl tragedy.