[单选题]
The energy gap between the valence and cokel*g7/z0 kp cn2wfhznkp,t . +duction bands in a certain semiconductor is 1.25 eV. Wha,fhp.k+ 2n wtzt is the threshold wavelength for optical absorption in this substance?
A. $599 \; nm$
B. $959 \; nm$
C. $873 \; nm$
D. $995 \; nm$
