19) B
Let faster driver be A
Let slower driver be B
Time of A = 1 minute 6 seconds = 66 seconds
Time of B = 1 minute 10 seconds = 70 seconds
Lapping means that the faster driver covered 1 more lap than the slower driver.
Let number of laps covered by B = n
Number of laps covered by A = n + 1
After lap 1, A would be 4 seconds ahead, after 2 laps, A would be 8 seconds ahead etc.
In order for A to lap B, we need the following equation to be satisfied:
66 x (n + 1) = 70 x (n)
66n + 66 = 70n
66 = 4n
n = 16.5 laps
So number of laps covered by A = n + 1 = 16.5 + 1 = 17.5
Time taken by A to cover 17.5 laps = 17.5 x 66 = 1155 seconds
1155 seconds = 19 minutes 15 seconds.