Mixing 0.1mol of NaOH, 0.1mol of ${\mathrm{HC}}_2{\mathrm{H}}_3{\mathrm{O}}_2$, and one liter of water, yields a solution which

Mixing 0.1mol of NaOH, 0.1mol of ${\mathrm{HC}}_2{\mathrm{H}}_3{\mathrm{O}}_2$, and one liter of water, yields a solution which is basic.

Acetic acid is used to transform sodium hydroxide solution into sodium acetate and water. A weak monoprotic acid is acetic acid. Its ${\mathrm{pK}}_{\mathrm{a}}$ value in aqueous solution is 4.76. Acetic acid (${\mathrm{CH}}_3\mathrm{COO}$) is the base of its conjugate. The pH of a 1.0 M solution, which is roughly the same as home vinegar, is 2.4, meaning that just 0.4% of the acetic acid molecules are dissociated.

Hence the option C is correct.