One reason for the difference between the British people working abroad and the average person at home is that the former ______.

A．Europeans are more intelligent than Africans and Asians
B．there is no such things as mental superiority
C．Europeans should share their knowledge with Africans and Asians
D．mental superiority is vital to the scientific progress in Europe

A．to warn the readers against misunderstanding the British people
B．to make a brief introduction to different social classes in Britain
C．to criticize the nonsense written about Britain
D．to describe the living conditions in Britain