The energy that should be added to an electron to reduce its de-Broglie wavelength from 1nm to 0.5 nm is

Question

$\begin {array} {1 1} (a)\;4 \: times\: the\: initial\: energy & \quad (b)\;equal\: to\: initial \: energy \\ (c)\;twice\: the\: initial \: energy & \quad (d)\;thrice \: the\: initial\: energy \end {array}$