Which distinction concerning solitary reports and witness numbers is correct?

Trustworthy Transmission, the Report of a Fāsiq, and Responsible Narration

• A solitary report is probative only with two corroborators at each level
• A reliable single report may be probative, whereas some kinds of testimony require multiple witnesses
• A solitary report becomes probative only after a courtroom testimony ruling
• Numerical requirements of testimony and report are always the same