Choice "B" is correct. Prenumbered receiving reports completed by the client's employees are considered internal evidence and are the least reliable of the items listed.Choice "d" is incorrect. Receivable confirmations received from client's customers, which are considered external evidence, are more reliable than internal evidence.Choice "a" is incorrect. Prior months' bank statements obtained from the client, which are considered external evidence, are more reliable than internal evidence.Choice "c" is incorrect. Municipal property tax bills prepared in the client's name, which are considered external evidence, are more reliable than internal evidence.