Which best explains long-run U.S. productivity growth?

While technological advancements play a role in productivity, slow population growth and inflation do not directly contribute to long-run productivity growth. A slow-growing population can limit labor force expansion, and inflation typically disrupts economic stability rather than fostering productivity improvements.

A steady population and constant education levels do not promote productivity growth. Instead, productivity benefits from an increasing, well-educated workforce, while tariffs can hinder productivity by restricting trade and increasing costs for businesses, thereby limiting their growth potential.

Although access to cheap raw materials can reduce costs, it does not inherently lead to productivity growth. Constant education levels fail to promote innovation and adaptability in the workforce, and while intellectual property rules can encourage innovation, they are not sufficient alone to drive long-term productivity without complementary investments in capital and education.