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．He believes that Thursday is the most productive day.
B．He found that the sense of smell influences memory.
C．He discovered that natural light makes us awake and alert.
D．He suggests that meeting rooms be put where there is enough natural light.