[单选题]
The energy gap betwens/2s; /wg:k dz 4rz 5cxjr0hven the valence and conduction bands in a ccgdne8y p9w x 08hc)-gertain semiconductor is 1.25 eV. What is the threshold wavelength for optical absoyxp8ew )h-89dc 0gng crption in this substance?
A. $599 \; nm$
B. $959 \; nm$
C. $873 \; nm$
D. $995 \; nm$
