[单选题]
The wave equation for hkwl- ge+ tg1u17cu4mc r rd/.pydrogen has .bw/ji8 e8 btri av),am.ql w2solutions only if the three quantum 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.