Answer is: C. H₂, molecule of hydrogen, g is chemistry abbreviations or physical state symbol for gas.
Lithium (Li) is solid (s) element (metal).
Water (H₂O) is liquid (l) compound or molecule.
Lithium hydroxide (LiOH) is aqueous solution (aq). It dissociates in water on lithium cation (Li⁺) and hydroxy anion (OH⁻).