According to the passage, which of the following is NOT true regarding polio?
A. One of the most incapacitating effects of polio was the fact that it made it difficult to breathe properly.
B. Whooping cough and pneumonia were both thought to be caused by polio infection.
C. The season and time of year seemed to have an impact on the spread of the crippling disease.
D. Children seemed to bear the brunt of the attack of the polio virus.