[" The ratio of the speed of the electron in the first Bohr orbit "],[" of hydrogen and the speed of light is equal to (where e,"h],[" and c have their usual meanings) - "],[[" A."2 pi hc/e^(2)," B."e^(2)c/2 pi h],[" c."e^(2)h/2 pi c," D."e^(2)/2 varepsilon_(0)hc]]