17. (5%) A rectangular pulse V_g(t) of an amplitude 15 (V) and a duration 1(μs) is applied through a series resistance R_g of 25(Ω) to the input terminals of a 50(Ω) Jossless transmission line. Given the speed of EM wave in this line is 1.5 x 10m⁸/ s. The line is 400 (m) long and short-circuited at the far end, as the figure shown below. Determine the voltage at the midpoint of the line at the time of 2 μs.

(A) 10V,
(B)-10V,
(C)OV,
(D)None of the above.