Two point charges q and 4q are at x=0 and x=l, respectively, and free to move. A third charge is placed so that the entire three-charge system is in static equilibrium.

Which source would provide the most bias-free information about smoking and increased health risks? a) a website created by heart disease patients b) a research study conducted by the mayo clinic eliminate c) a public service message sponsored by tobacco companies d) an online question forum conducted by attorneys for cardiac specialists