[单选题]
The wave equation for9o pedo/m i8;u hydf3bgsbzv -4c0m2 m k3) z4cd,hmn zf8hrogen has solutions 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.
