The correct option is C C55H72O5N4Mg
Photosynthesis takes place in the green leaves of plants and other green parts of plants like stem etc. The most active photosynthetic tissue in higher plants is the mesophyll of leaves. Mesophyll cells have many chloroplasts, which contain the specialized light-absorbing green pigments, the chlorophylls. When chlorophyll absorbs light, it gets excited and emits electrons. Chlorophyll a is the primary photosynthetic pigment. It shows bright or blue-green colour in the chromatogram. Chlorophyll a is directly involved in the light reaction of photosynthesis. It is present in the reaction centres of Photosystem I and Photosystem II which absorbs light energy of longer wavelength. These centres can release electron upon absorption of energy. A chemical formula which shows the simplest ratio of elements in a compound rather than the total number of atoms in the molecule is known as empirical formula. The empirical formula of chlorophyll a is C55H72O5N4Mg.