A plane monochromatic light falls normally on a diaphragm with two narrow slits separated by a distance d = 2.5 mm. A fringe pattern is formed on the screen placed at D = 100 cm behind the diaphragm. If one of the slits is covered by a glass plate of thickness `10mu m`, then distance by which these fringes will be shifted will be :
A. 2 mm
B. 3 mm
C. 4 mm
D. 5 mm