The correct answer is D. 8 kmph.
The speed of the second train on double line section running on T/A602 is 8 kmph. This is because the first train is running at 10 kmph, and the two trains are separated by a distance of 200 meters. The safe following distance between two trains is 100 meters, so the second train must slow down to 8 kmph in order to maintain a safe distance.
Option A is incorrect because the speed of the second train cannot be more than the speed of the first train. Option B is incorrect because the speed of the second train cannot be more than the safe following distance. Option C is incorrect because the speed of the second train cannot be less than the safe following distance.