Downstream speed =7.5+1.5=9 km/h. Upstream speed =7.5−1.5=6 km/h. Let distance =d. Time =9d+6d=6050=65. So 182d+3d=65, giving 185d=65, hence d=3 km. Answer is 3 km.
Note: Option 1 gives 3 km which is the correct answer; the chosen option 2 (2.9 km) appears to be incorrect.