What is the definition of "soundness" in an argument?

Soundness in an argument refers to a twofold attribute: one that incorporates both validity and the truth of the premises. For an argument to be considered sound, it must meet two criteria: it should have a valid structure, meaning that if the premises are true, the conclusion must also be true, and all the premises must indeed be true. Therefore, option C accurately captures the essence of soundness by emphasizing the necessity for all premises to be both true and valid. This concept ensures that not only does the argument chase a logical form, but it also hinges on a foundation of factual accuracy, providing a robust basis for the conclusion reached.

In contrast, other options either misinterpret soundness, such as suggesting failure of premises or misleadingly focusing on emotional appeal, which is not a criterion for assessing logical arguments. Validity alone does not encompass the truth of premises, making the full definition of soundness specifically hinge on both true premises and valid reasoning.