How many litres of water must be added to 1 litre of an aqueous solution of HCl with a pH of 1 to create an aqueous solution with $pH$ of $2$ ?

Question

$\begin{array}{1 1} (1) 0.1\;L \\ (2) 0.9\;L \\ (3) 2.0\;L \\(4)9.0\;L \end {array}$