PLS PLS PLS QUICK (EXPLANATION TOO)
Major scientific theories include the cell theory, the big bang theory, and the theory of plate tectonics. How are scientific theories formed?

A. through a single scientific discovery in which a scientist learns something new B. through the formation of several related hypotheses
C. through meetings between scientists in which they discuss several possible answers to a scientific question
D. through extensive testing and the accumulation of several lines of evidence