Chang Lee, an eight-year-old boy, eats steak at a restaurant. Two days later, he develops fever, throws up anything he consumes, and suffers from abdominal pain. Clinical diagnosis shows that Chang Lee is affected by food poisoning because the steak he ate was contaminated. The two days' time period between Chang Lee's consuming the steak and the emergence of his sickness is called the _____.
A) refractory period
B) gestation period
C) transition period
D) incubation period
Question 2
Dichloro-diphenyltrichloroethane (DDT) was banned in the United States in 1972 because:
A) it was found to destroy crops.
B) it was found to help mosquito breeding.
C) it was found to decrease crop yields.
D) it was found to damage wildlife.