Find the suitable word for blank “a”.

Paragraph for question 9 to 12 Chlorophyll pigments, specifically a and b, play a crucial role in photosynthesis and are produced within the chloroplasts of leaf tissues. These molecules possess hydrophobic characteristics due to their phytol tail, and their structure resembles hemoglobin, except chlorophyll holds a magnesium ion at its core instead of iron. Synthesizing chlorophyll is resource-intensive, requiring nitrogen atoms, and as leaves age, the chlorophyll breaks down, with the plant reabsorbing much of the nitrogen for future use. Apart from Chlorphyll there are other pigments like a pigment which is primarily involved in protecting plant tissues from excessive light by absorbing harmful ultraviolet radiation. Some of the pigments like b_ water-soluble and often found in the vacuoles of plant cells. Based on the given paragraph answer the following questions: