Oxford University would be excluded out of those universities that receive PhD grants from ESRC, because the completion rate of its PhD students' theses within four years is lower than ______.

A．all the institutions on the blacklist are arbitrary and negative
B．there is no hard evidence to prove that faster completion rates result from greater efficiency rather than lower standards or less ambitious doctoral topics
C．many of the best students go quickly into jobs where they can apply their research skills, but consequently take longer to finish their theses
D．some polytechnics are penalized by random fluctuations in student performance

A．force departments to give graduates more teaching time
B．try to persuade universities to change their ways
C．dictate the standard of thesis required by external examiners
D．note that students want more research training and less elaborate style of thesis