With respect to the constituents causing alkalinity in water, which of the following situation never arises?

Question

$\begin{array}{1 1} (a)\; CO_3^{2-}\; and\; HCO_{3}^–\; together \\ (b)\; HCO_{3–} \;and\; OH^{–}\; together \\ (c)\; OH^{–}\; only \\ (d)\; OH^{–}\; and\; CO_3^{2-}\; together \end{array} $