P walks around a circular field at the rate of two rounds per hour while Q runs around it at the rate of eight rounds per hour. They start in the opposite direction from the same point at 6.45 a.m. They shall first cross each other at? a) 6.45 a.m b) 6.50 a.m c) 7.51 a.m d) 6.51 a.m e) 7.45 am