Which of the following is a characteristic of science? Select one:
a. It asks questions about the natural world.
b. It asks questions that cannot be tested.
c. It is done by only one scientist at a time.
d. It uses opinions to make conclusions.

Two technicians are discussing how to test a car's exhaust by holding a small piece of paper within an inch of the tailpipe mouth. technician a says that if the paper is vibrating due to a "puffing" output from the tailpipe, this signals a smoothly running engine. technician b says that if the paper is being drawn toward the tailpipe, this could indicate burned exhaust valves. who is correct? a. technician b b. both technicians a and b c. technician a d. neither technicians a or b