ANS:C - meta

The chemical formula HPO3 corresponds to metaphosphoric acid. Metaphosphoric acid, also known as polyphosphoric acid, is a condensed form of phosphoric acid where the phosphate units are linked together by oxygen atoms in a linear chain. It is represented by the formula (HPO3)n, where n denotes the number of phosphate units in the chain. Metaphosphoric acid is commonly used in organic synthesis and as a dehydrating agent in chemical reactions.