B. 120 Min
Feedback Seema is quickest girl one complete round on Neetu, the slowest girl, in 3000/200-125 or 40 minutes.
Seema gains one complete round on Kiran, the next slowest girl in 3000/200-150 or 40 minutes.
Thus, Seema and Nitu are together after every 40 minutes, and Seema and Kiran are together after 60 minutes.
'Hence, Seema, Kiran and Nitu will be together in the time which is LCM of 40 and 60. The LCM of 40 and 60 is 120 minutes or 2 hours.