What type of evidence can witnesses provide in criminal cases?

Witnesses in criminal cases primarily provide factual testimony that supports the case. This type of evidence can include personal observations, experiences, or knowledge regarding the events in question. Testimonies from witnesses are crucial as they can establish facts surrounding the circumstances of the crime, identify individuals involved, and confirm or negate the actions of the accused.

The other options, while they provide information relevant to legal settings, do not fit the role of witnesses. Written agreements between parties and legal documents are typically part of the documentation presented in court, rather than something a witness would directly testify about. Statistical data, while useful for providing context or background information, does not come from individual witness experiences and cannot replace the direct, personal testimony needed to substantiate claims in a criminal case.