In chemistry, acids and bases play a critical role in various chemical reactions and processes. An acid is defined as a substance that donates protons (H⁺) and a base as a substance that accepts protons. The strength of an acid can be measured by its dissociation constant (K_a). Consider the following equation:

HA <=> H⁺ + A^-

Where HA represents the acid. Based on the properties of acids and bases, which of the following substances is most likely to be classified as a strong acid?