Two plane, smooth surfaces are parallel to each other and are initiallt a distance of 2 metre apart. The two surfaces approach each other with a velocity of `1 cm//sec`. A particle starts with a velocity of 4 cm/sec from one surface and collides normally and elastically on the other surface from the time the two surfaces start moving. The collisions continues back and forth till the surfaces touch each other. The total distance covered by the particle is :
A. 2 m
B. 1 m
C. 4 m
D. 3 m
