Cyanobacteria are related to eukaryotes in having:

Explanation

The correct answer is Option C: Both A and B. Cyanobacteria and eukaryotes share Photosystem I (PSI) and Photosystem II (PSII) as part of their photosynthetic machinery. These photosystems are essential for converting light energy into chemical energy during photosynthesis. PSI captures light energy to facilitate the transfer of electrons, while PSII uses light energy to extract electrons from water, releasing oxygen. Options A and B are incorrect because they only mention one of the photosystems, whereas both are necessary for the full range of photosynthetic functions shared between cyanobacteria and eukaryotes. Option D is incorrect because cyanobacteria do possess these photosystems.