The correct option is A strong acid
A strong acid is one that completely ionizes (dissociates) in a solution (provided there is sufficient solvent). Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO4), nitric acid (HNO3) and sulfuric acid (H2SO4). In aqueous solution, each of these essentially ionizes 100%.