What constitutes a logical fallacy?

A logical fallacy refers to an error in reasoning that undermines the validity of an argument. When an argument is built on a faulty premise or contains flawed reasoning, it fails to hold up under scrutiny; thus, the conclusion it reaches is not reliably supported. For example, this could occur through the use of irrelevant information, misinterpretation of evidence, or oversimplification of complex issues. This definition aligns precisely with option B, as it highlights that the essence of a logical fallacy lies in the breakdown of logical reasoning, which ultimately weakens the argument's effectiveness.

In contrast, the other options represent concepts that do not embody the nature of a logical fallacy. A valid argument supported by facts indicates solid reasoning and reliability, while evidence that strongly supports a conclusion signifies strong logic rather than a fallacy. Lastly, a statement that is always true does not align with logical fallacies, which focus on reasoning errors rather than truthfulness. Understanding logical fallacies is crucial for evaluating arguments critically and effectively.