What instruction does the author have in his mind by asking you to imagine you have a magic wand

A．He should try to be as creative as possible.
B．He may set up a problem and then try to conceive all the possible solutions to it.
C．He should study all the techniques mentioned in the passage and try to use them.
D．He should play a different role from the one he plays now

A．helped to overcome the physical discomforts the divers suffered when nitrogen was used.
B．was found by Dr.J. Hildebrand for deep - sea - diving.
C．is now still generally acknowledged as standard practice for deep- sea diving
D．may be thought to contain all the information stated in A, B, and C