[单选题]
The mass of an atom eg5es 1a f/olq )n0xo2ek 52ldzn)f1ho- lg x*xiv85/h rbt7jis
A. approximately equally divided between neutrons, protons, and electrons.
B. evenly divided between the nucleus and the surrounding electron cloud.
C. concentrated in the cloud of electrons surrounding the nucleus.
D. concentrated in the nucleus.
