Speed of the last train during ACF on double line is ________ km/h. A. 25/10/Walking B. 20/10/Walking C. 20/15/Walking D. None of these

The correct answer is D. None of these.

The speed of the last train during ACF on double line is not given in the question. The options A, B, and C are all incorrect.

Option A is incorrect because it is not a valid speed. The speed of a train must be a positive number.

Option B is incorrect because it is not a valid speed. The speed of a train must be a positive number and greater than 0.

Option C is incorrect because it is not a valid speed. The speed of a train must be a positive number and greater than 0.

The correct answer is D. None of these.