[单选题]
The energy gap between the valencdn;pmxr9xl1f 9ccb*/pv ( t. :tp (eyee and conduction bandf cvharyw 508 j/l;o-ts in a certain semiconductor is 1.25 eV. What is tjr5 /af;08 vhlwo- ctyhe threshold wavelength for optical absorption in this substance?
A. $599 \; nm$
B. $959 \; nm$
C. $873 \; nm$
D. $995 \; nm$
