The reaction center of photosystem has:

Explanation

The reaction center of a photosystem is crucial for the initial steps of photosynthesis. It consists of one or more molecules of chlorophyll a, which are responsible for capturing light energy, and a primary electron acceptor that facilitates the transfer of electrons. Option C correctly identifies these components. Option A is incorrect, as it suggests only one molecule of chlorophyll a, whereas the center can have multiple such molecules. Option B is misleading, as it suggests an unspecified large number. Option D incorrectly includes chlorophyll b, which is not part of the reaction center but is involved in light harvesting.