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 idiomatic error. Identify the part that contains the error. If there is no error, choose option (

• E . The officer blamed himself (a) / for the delay in processing the file (b) / even though the mistake was caused (c) / by systemic inefficiencies (d). / No error (e)