Cyanobacteria participate in multilayered microbial mats with sulfur phototrophs. These other phototrophs absorb light if they lie below the cyanobacteria by

A) growing anaerobically.
B) producing phycocyanin.
C) absorbing light at shorter wavelengths than cyanobacteria.
D) absorbing light at longer wavelengths than cyanobacteria.
E) absorbing UV irradiation.