[单选题]
An electron is moving about a sinr52k-+*n .r u m*l5b miundjl u59belbgle proton in an c8v ;fw n):tv/equ/agu *+ebiorbit characterized by n = 4. How many of thb ;) vwn* /q:iev/eafuut+8c ge electron's de Broglie wavelengths fit into the circumference of this orbit?