For 50 points.
tim wants to study how air currents affect weather patterns around the earth. during his study, he makes several assumptions based on accepted scientific knowledge, including

-the earth is round;

-warm air rises over cooler air;

-the sun is the main source of energy for many earth processes.

is it acceptable for tim to make these assumptions during his investigation?

a. yes; when performing a scientific investigation, accepted scientific facts can be assumed to be valid.

b. yes; a scientific investigation can be based on any assumptions, as long as they are clearly stated.

c. no; tim must scientifically prove that all of the assumptions are valid as part of his investigation.

d. no; assumptions are never permitted in a scientific investigation.