Chlorophyll and bacteriochlorophyll pigment molecules absorb light energy for photosynthesis. each specific version of these molecules absorbs a different range of wavelengths of light, allowing different species of phototrophs to coexist by partitioning their use of the light spectrum. what controls the absorption spectrum of each particular chlorophyll/bacteriochlorophyll?

a. the various substituents on the tetrapyrrole ring alter the absorption properties of the pigments.
b. the number of tetrapyrrole rings linked together alters the absorption spectrum.
c. the exact orientation of the pigment molecule in the membrane (on the membrane surface, inner membrane or transmembrane) alters the absorption spectrum.
d. the specific metal ion in the center of the tetrapyrrole ring alters the absorption spectrum.