Which of the following countries would have the most difficulty responding to rapid population growth?

Italy has a declining population due to low birth rates and an aging demographic. This demographic trend suggests less pressure from rapid population growth, allowing Italy to manage its social services and infrastructure more easily, as the country is currently experiencing a population contraction rather than expansion.

Similar to Italy, Spain has a low birth rate and is dealing with an aging population. While Spain faces economic challenges, the lack of significant population growth alleviates some of the pressure on its resources and public services, making it less difficult to respond to the existing demographic trends compared to countries with rapid growth.

The United States, while experiencing population growth, has a more developed infrastructure and a higher capacity to manage such growth compared to India. The diverse economy and established social systems allow the U.S. to address population changes more effectively, even with immigration contributing to its growth.