Which is the closest synonym for the word solidify, as it is used in the article?

The closest synonym for the word “solidify” in the context of an article would be:

A. strengthen

Explanation: “Solidify” often means to make something stronger or more definite. In many contexts, such as ideas or plans, it implies reinforcing or establishing them firmly. Therefore, “strengthen” aligns well with this meaning. If you have more questions or need further clarification, feel free to ask!