Final answer:
In the Solow growth model, human capital will increase if workers are better educated. Higher levels of education and skills make workers more productive and contribute to economic growth. Therefore, the correct option is b. workers are better educated.
Step-by-step explanation:
In the Solow growth model, human capital will increase if workers are better educated. This means that option b, workers are better educated, is the correct answer. When workers have higher levels of education and skills, they become more productive and can contribute more to the economy. With increased human capital, workers can create new technological innovations that can lead to further economic growth.