What does "unsound" imply when describing an idea?

The term "unsound" when describing an idea indicates that the idea lacks a solid foundation or is not reliable or valid. This can refer to logical reasoning that is flawed or conclusions that are based on inadequate evidence. Essentially, if an idea is described as unsound, it suggests that it is not well-supported and may lead to misleading or incorrect conclusions. This is why the choice that states "that it is not solid or healthy" fits perfectly with the meaning of "unsound," as it directly captures the essence of an idea that is fundamentally flawed or untrustworthy. The other choices imply positive characteristics or qualities of an idea, which contrasts with the implication of weakness or deficiency associated with the term "unsound."