A and B walk around a circular track. They start at 8 a.m. from the same point in the opposite directions. A and B walk at a speed of 1 rounds per hour and 1 rounds per hour respectively. How many times shall they cross each other before 9.30 a.m. ?	Select:
A) A)5  B) B)6  C) C)8  D) D)3  E) E)9
Relative speed = 1 + 1= 
<gadget id="calculator">1 + 1</gadget>
<output>2</output>
2 rounds per hour.   So, they cross each other 2 times in an hour and 1 times in half an hour.   Hence, they cross each other 3 times before 9.30 a.m.   ANSWER:3
<result>D</result>
A and B walk around a circular track. They start at 8 a.m. from the same point in the opposite directions. A and B walk at a speed of 1 rounds per hour and 1 rounds per hour respectively. How many times shall they cross each other before 9.30 a.m. ?