According to the study discussed in the second paragraph, which of the following weekdays is the most productive

A．you can change a person's nature for a while, but you can't change it permanently
B．you can change man's living conditions, but you can't change his nature
C．you can follow biological roles but you can't break them
D．you can improve yourself but you can't change your nature

A．the readers of Private Eye
B．the powerful people satirized by Private Eye
C．the British public
D．the common people exploited by those in power