$\Delta ABC \sim \Delta DEF$,ar $(\Delta ABC)=9 cm^2$,ar $(\Delta DEF)=16 cm^2$.If $BC=2.1$ cm, then the measure of EF is

Question

$\begin{array}{1 1}2.8\;cm\\4.2\;cm\\2.5\;cm\\4.1\;cm\end{array} $