Final answer:
In bacteria, photosystems are predominantly located in the cell membrane within specialized structures for photosynthesis. Option a is correct.
Step-by-step explanation:
In bacteria, the location of photosystems is predominantly found in cell membrane structures specialized for photosynthesis. Some prokaryotic cells, such as cyanobacteria and photosynthetic bacteria, have membrane structures like thylakoids, chromatophores, or chloroforms which are infoldings of the plasma membrane containing photosynthetic pigments.
In contrast to eukaryotic cells, where photosynthesis takes place inside chloroplasts, these prokaryotic cells conduct photosynthetic processes directly within the infolded regions of the plasma membrane. Therefore, the correct answer to the question is a) Cell Membrane.