The concentration in mole per liter of hydronium ion $$[\mathrm{H_3O^+}]$$ for a solution having pH $$8.26$$ is

A

$$10^{-7}$$

B

$$1\times10^{-9}$$

C

$$5.5\times10^{-9}$$

D

$$3.2\times10^{-3}$$