Solution:Panini's Siva-sutras organize Sanskrit sounds into phonological classes using pratyaharas. The pratyahara ac is formed from the first sound a up to the marker c, and this range includes all vowels of Sanskrit: a, ā, i, ī, u, ū, r, ī, 1, e, ai, o, au. Panini uses ac to collectively refer to the full vowel inventory, which is crucial in rules of sandhi and morphological operations in Sanskrit grammar.