Solution

Chlorophyll a is termed as universal photosynthetic pigment as it is found in all photosynthetic plants except bacteria. It is also called primary photosynthetic pigment because it performs primary reaction of photosynthesis which involves conversion of light chemical energy. Other photosynthesis pigment chlorophyll b and carotenoids (carotenes and xanthophylls ) are called accessory pigment, as they absorb light energy of different wavelengths, broaden the spectrum of light absorption and hand over the energy to chlorophyll a through electron spin resonance. So, the correct answer is 'Chlorophyll a'.