What real-world issue does the author refer to by using a lifeboat metaphor in "lifeboat ethics: the case against the poor"?
a. reproduction, in regard to how poorer nations have a much higher rate of population growth
b. starvation, in regard to how many people need food supplied by other countries in order to survive
c. foreign policy on immigration, in regard to how many people can live in a country and still preserve its resources
d. racism, in regard to how many people use prejudice to decide who gets food and who doesn't