Correct Answer: Carl Scheele 

Solution : The correct option is - Carl Scheele .

Carl Wilhelm Scheele was a Swedish German pharmaceutical chemist. 

By heating mercuric oxide, silver carbonate, magnesium nitrate, and other nitrate salts, Scheele discovered oxygen.

He also discovered hydrofluoric, hydrocyanic, and arsenic acids, as well as the organic acids tartaric, oxalic, uric, lactic, and citric.