[单选题]
The energy gap between the valence and conduction bands in a certw ftmm1h;z0u g3cv7k7ain. 3l5zbzapc9v semiconductor is 1.25 eV. What is the threshold wavelength for opticvzb.p azc5l3 9al absorption in this substance?
A. $599 \; nm$
B. $959 \; nm$
C. $873 \; nm$
D. $995 \; nm$
