The phrase that defines a sound argument is "a sensible and valid statement". To determine this answer, it is helpful to understand the qualities of a sound argument. A sound argument is logically valid, which means that the conclusion follows logically from the premises. In addition, the premises of a sound argument are true and relevant to the conclusion. Therefore, a sound argument consists of sensible and valid statements, as they are both logical and true. The other options, such as "a loud remark" and "a popular opinion", do not necessarily meet the criteria of a sound argument, as they do not necessarily contain logical reasoning or true premises. The option "an impractical analysis that is hard to prove" also does not define a sound argument, as it suggests an analysis that may be difficult to support or demonstrate with evidence.
The phrase that defines a sound argument is "a sensible and valid statement."
