Chapter 16.4, Problem 2CP

What is the concentration of $\text{HBr}$ in a solution with pH 5.89 at $\text{25°C}$ ?

$\begin{array}{l}\text{a)}\\ 7.8\times {10}^{-9}M\\ \text{b)}\\ 1.3\times {10}^{-6}M\\ \text{c)}\\ 5.9\times {10}^{-14}M\\ \text{d)}\\ 8.1\times {10}^{-7}M\\ \text{e)}\\ 1.0\times {10}^{-7}M\end{array}$