The researchers decided to study the effects on breathing first because __________ might appear in a later period of time.

A．It requires a great deal of time.
B．It requires the spirit of dedication.
C．It requires the spirit of cooperation.
D．It requires all the representatives to write down their names and telephone numbers.

A．They are unimportant and should be disregarded.
B．They may give us helpful clues about ourselves.
C．Only a trained psychologist can interpret them with success.
D．They should never be interpreted literally.