C) [tex]\text{HCl}[/tex] hydrochloric acid and, in case that the question allows for more than one choices, D) [tex]\text{CO}_2[/tex] carbon dioxide as well.
Methane molecules [tex]\text{CH}_4[/tex] are nonpolar and barely dissolve in water.
Sodium hydrocarbonate [tex]\text{Na}\text{HCO}_3[/tex] undergoes hydrolysis to release hydroxide ions [tex]\text{OH}^{-}[/tex] that can end up consuming [tex]\text{H}^{+} \; (aq)[/tex]:
[tex]\text{NaHCO}_3 \; (aq) \to \text{Na}^{+} \; (aq) + \text{HCO}_3^{-} \; (aq)\\\text{HCO}_3^{-} \; (aq) + \text{H}_2\text{O} \; (l) \leftrightharpoons \text{H}_2\text{CO}_3\; (aq) + \text{OH}^{-} \; (aq)[/tex]
Hydrochloric acid, a strong acid, ionizes to produce protons [tex]\text{H}^{+} \; (aq)[/tex] and chloride ions when dissolved in water:
[tex]\text{HCl}\; (aq) \to \text{H}^{+} \; (aq) + \text{Cl}^{-} \; (aq)[/tex]
Carbon dioxide reacts with water to produce hydrocarbonic acid, a weak acid that slightly ionizes, also producing protons [tex]\text{H}^{+} \; (aq)[/tex] but to a significantly lesser extent than hydrochloric acid does.
[tex]\text{CO}_2\; (g) + \text{H}_2\text{O} \; (l) \leftrightharpoons \text{H}_2\text{CO}_3\; (aq)\\\text{H}_2\text{CO}_3\; (aq) \leftrightharpoons \text{H}^{+}\; (aq) + \text{HCO}_3^{-} \; (aq)[/tex]
