Yoko has a utility function such that U$($W$)=$W$^0\mathrm{.}5.$ She spent all her wealth on shares of a company providing a new electronic money. The company is going to have an initial public offering $($IPO$)$ tomorrow. Yoko believes that her shares worth $$625$ with $60\%$ probability and $$225$ with a $40\%$ probability. What is her expected utility?

A $225$

B $21$

C $28$

D $625$