Which of the following best describes exculpatory evidence?

Exculpatory evidence is best defined as evidence that can potentially clear a defendant from guilt in a criminal case. This type of evidence supports the defendant's claims of innocence and may show that they did not commit the crime for which they are being accused. It plays a crucial role in ensuring a fair trial, as it can affect the outcome by leading to the defendant's acquittal if sufficiently compelling.

The other options do not accurately capture the essence of exculpatory evidence. Evidence that proves a defendant's guilt would be classified as inculpatory, directly opposing the nature of exculpatory evidence. Information regarding witness reliability pertains to evaluating the strength or credibility of witness testimony rather than directly addressing a defendant's potential guilt or innocence. Lastly, evidentiary material that cannot be used may refer to evidence that is inadmissible in court, which does not fulfill the criteria of supporting or clearing a defendant's charges. Thus, the definition of exculpatory evidence aligns closely with the description provided in the correct choice.