To solve this problem, the user needs to know the concept of distance = speed x time and the concept of relative speed.

Let d be the distance travelled by the freight train before it was overtaken by the passenger train.

Let s be the speed of the freight train.

The passenger train overtakes the freight train after traveling 4 hours. Hence, the passenger train covers a distance of d + 4s.

Since the passenger train overtakes the freight train, the distance covered by the freight train is equal to the distance covered by the passenger train. That is,

d = d + 4s - 4 x 16

where 4 x 16 is the distance covered by the passenger train in 4 hours.

Simplifying the above equation, we get:

4s = 64

s = 16

Therefore, the average speed of the freight train was s = 16 km/hr.

Option A) 40, Option B) 30, Option C) 80, and Option D) 60 are incorrect.

Option A) 40 is incorrect because we have already calculated the average speed of the freight train to be 16 km/hr.

Option B) 30 is incorrect because we have already calculated the average speed of the freight train to be 16 km/hr.

Option C) 80 is incorrect because it is too high and not possible given the information in the problem.

Option D) 60 is incorrect because it is too high and not possible given the information in the problem.

Therefore, the answer is:

The Answer is: A. 16