D. entry will be blocked even if firms are earning high profits. "
Explanation:
"Barriers to entry" is an economic term that represents the establishment of factors that prevent or hinder a company from starting to operate in a certain segment of the market, even if that company has a high profit margin. These barriers can present economic, technical and legal factors.
With that, we can say that "If the North American newsprint paper market has barriers to entry, then entry will be blocked even if firms are earning high profits."
