[单选题]
An electron is moving .x8ci2uaz ku/ 74hw ,ifbgn p-abo)cw3 tib0*7/u6 ndwz z5hdu c8wb xc8cut a single proton in an orbit characterized by n = 4. Ho3ci b57c8cdt)0hwc*8w 6 xbz ud/wuz nw many of the electron's de Broglie wavelengths fit into the circumference of this orbit?
