The standard deviation of returns of a particular stock is $43\%$ and that of the market is $35\%.$ The coefficient of correlation between the returns of the stock and that of the market is $0\mathrm{.}25.$ The real risk$-$free rate is $2\%$ and the expected inflation rate is $1\mathrm{.}5\%.$ What is the stock's contribution to risk $($beta$)?$

$1\mathrm{.}23$

$3\mathrm{.}26$

$0\mathrm{.}31$

$0\mathrm{.}81$

$0\mathrm{.}20$