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.
No; Tim must scientifically prove that all of the assumptions are valid as part of his investigation.

B.
No; assumptions are never permitted in a scientific investigation.

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

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