The cruising speed of the aircraft is 500 kmph. If there is a head wind of 50 kmph, then the air speed and ground speed of the aircraft respectively will be_________________?
A. 450 kmph and 500 kmph
B. 500 kmph and 450 kmph
C. 450 kmph and 450 kmph
D. 500 kmph and 500 kmph