[单选题]
The wavelength of a ruby laser is 694.3 nm. What is the energy difference bia9 hg-dect8np+1 8g jbt,p+b+q t*eco iuep ;oi4y0al)p5- 5t inv7vetweei5 lp-eqtcy p;v7o5i enatiu )v+0 *o4n the two energy states involved in laser action?
A. $1.537 \; eV$
B. $1.646 \; eV$
C. $1.786 \; eV$
D. $1.812 \; eV$