The correct answer to the question is option 4 - None of these.

Option 1, u;!/(2g), is not the correct expression for the final velocity when the body attains maximum height. This expression does not consider the effect of gravity on the body`s motion.

Option 2, 2g/u2, is also not the correct expression. This expression incorrectly suggests that the final velocity is dependent on the square of the initial velocity. In reality, the final velocity at maximum height is only determined by the acceleration due to gravity.

Option 3, u``g/2, is another incorrect expression. It introduces an unknown variable, "u``," which is not defined in the question. Additionally, the expression does not account for the effect of gravity on the body`s motion.

Therefore, since none of the given options provide the correct expression for the final velocity at maximum height, option 4 - None of these is the correct answer.