[单选题]
For a diatomic quantum mechanical vibraasxs.l;w :a /1t1(q 1e(ldm mlssv)rxtor qc+3at(foh:k, the energy difference between adjacent +o aq3cfk( th:quantum states
A. increases as v increases.
B. decreases as v increases.
C. is constant for all values of v.
D. varies randomly as v increases.