Each of the following sentences has been divided into five parts (a), (b), (c), (d) and (e). One of these parts may contain a grammatical or contextual error. Identify the part that contains the error. If there is no error, choose option (e). The historian rarely acknowledges opposing viewpoints (a), / even when presented with strong archival evidence (b),/ which challenges his long-held assumptions (c),/ doesn’t he (d)?/   No error (e)