[单选题]
The wavelength of a ruby laser i:she+x cy c)6is 694.3 apz5e+*ms1e ,9tge+ twzg uy59v s jr9nm. What is the energy difference between the two enyuegwg9v+az+r1 psj5 t9sem*9, e5tz ergy states involved in laser action?
A. $1.537 \; eV$
B. $1.646 \; eV$
C. $1.786 \; eV$
D. $1.812 \; eV$