The word "assert" (line 4, paragraph 3) might mean______.

A．is used both as a cultural and a physical object
B．serves different purposes equally well
C．is utilized by man
D．can be of use to both man and animal

A．give rise to feelings of hostility among scientists of different branches
B．involve an increasing number of scientists in a lot of extra work
C．get scientists directly involved in research projects with immediate industrial applications
D．yield fewer results with a greater amount of manpower and materials