As Hurricane Katrina approached New Orleans in 2005, the city issued orders to evacuate. Not everyone evacuated. After the storm hit, there were many efforts to lend aid. However, some people objected to the aid, saying that those who stayed behind had chosen their own fate. The people who voiced objections to the aid demonstrated which of the following?
a. Diffusion of responsibility
b. The norm of social justice
c. The effects of the arousal: cost-reward tradeoff
d. Kin selection