An electron is trapped in an infinitely deep rectangular well with sides of length $L_x = L$ and $L_y = 2L$. The energy that the electron needs to move from the ground state to the state $n_x = 2$, $n_y = 4$ is:
$\frac{2h^2}{mL^2}$
$\frac{3h^2}{mL^2}$
$\frac{2m L^2}{h^2}$
$\frac{mL^2}{7h^2}$
$\frac{8mL^2}{27h^2}$