A．It's of significance to make different reactions to the same things.
B．Scientific research is unreliable owing to the different observations.
C．People try their best to make impartial observation.
D．The way of observation varies from person to person.

A．objectivity is essential to scientific research
B．hypothesis is based on careful observation
C．creativeness plays an important part in scientific research
D．observation is the only factor determining scientific research