[单选题]
An electron is moving about a single proton in an ig*jvf. f )xe.orbit characterized by lv 4qyjg5r,x)5.zm e+pz,gs 2nocgc 4 n = 4. How many of the electron's de Broglie wavelengths fit into the circumference4)lr5z gn,ggsccvq xeo+54 ,zj.y m2p of this orbit?
