In the box "World Population Could Go from Boom to Bust," the textbook describes emerging population issues. What challenge do experts say many nations will now face into the next century?

A. Declining birth rates and an aging population will bring widespread difficulties in maintaining a young workforce and sustained economic growth.
B. Declining birth rates will mean that most nations will be unable to sustain stable population levels, causing an alarming drop in the global population.
C. Population growth in developing nations will trigger political instability, while population decline in developed nations will lead to economic deterioration.
D. Exploding population growth will lead to a chronic shortage of food, housing, energy, and other resources.