Hand shunting of wagons is totally prohibited in gradients A. 1 in 400 OR Steeper B. ST 1- IN 400 C. 1 in 260 D. None of these

The correct answer is: A. 1 in 400 OR Steeper

Hand shunting of wagons is totally prohibited in gradients of 1 in 400 or steeper. This is because the wagons can become unstable and derail if they are shunted on a gradient that is too steep.

Option B, ST 1- IN 400, is not a valid option. Option C, 1 in 260, is a valid option, but it is not the correct answer. Option D, None of these, is not a valid option.