An electron is 2000 times lighter than a proton. Both are moving such that their matter waves have a length of $1\: \dot {A}$. The ratio of their kinetic energy in approximation is

Question

$\begin {array} {1 1} (a)\;1:1 & \quad (b)\;1: 2000 \\ (c)\;2000:1 & \quad (d)\;1:200 \end {array}$