[单选题]
The wave equation for hydrogen has soluti4usy+5xr -s qr)m1zjt ons only if the three quantumg (jo9 5p nd;xqgw)r1m numbers $n$, $l$, and $m_l$ meet certain conditions. One of these conditions specifies that n
A. can be any real number.
B. can be any non-negative integer.
C. can be any integer.
D. can be any positive integer.
