In a Young double slit experiment, the distance between the slits is 50 μm and the distance of the screen from the slits is 5 cm. An infrared monochromatic light is mood to produce an interference pattern with fringe width 1 mm. If the light source is replaced by an electron source to produce the same fringe width then the speed of the electrons is approximately
A. 700 m/s
B. 7000 m/s
C. 70 m/s
D. 70000 m/s