Two cars X and Y travelling in opposite directions along the same high way at uniform velocities 110 kmh^-1 and 90kmh^-1 respectively pass each other at a certain point. The velocity of X relative to Y at the time they pass each other is

• A.200 kmh^-1
• B.100 kmh^-1
• C.40 kmh^-1
• D.20 kmh^-1