Based on the charts, what will most likely happen to the populations of the world and the United States?

Both will continue to decline at a steady rate.
Both will continue to grow at a steady rate.
The world’s population will keep going up, but the US population will drop.
The world’s population will level off, but the US population will increase.

Based on the provided information, the world's population is projected to continue growing at a steady rate, while the population of the United States is expected to increase as well. Therefore, the correct answer is: "The world’s population will keep going up, but the US population will also increase."