question_answer

The traffic lights at three different road crossings change after every 42 seconds, 56 seconds and 63 seconds, respectively. If they change simultaneously at 9 : 30 : 00 hours, then at what time will they again change simultaneously?

A)  9 : 37 : 12 hrs 

B)  9 : 38 : 12 hrs

C)  9 : 38 : 24 hrs              

D)  9 : 38 : 14 hrs

E)  None of these