Arun has travelled 60 km when Barun starts.
Barun overtakes Arun in $\frac{60}{40-30}$ = 6 hrs
In this time, Barun travels 6 × 40 = 240 km from the starting point.
Kiranmala overtakes Arun at the same point.
Kiranmala takes $\frac{240}{60}$ = 4 hrs to reach there.
Arun takes $\frac{240}{30}$ = 8 hrs to reach there.
Kiranmala starts 8 – 4 = 4 hrs after Arun.
Hence, option (3)4 is the Answer.