Choose the correct answer from the given four options. Equations of diagonals of the square formed by the lines x = 0, y = 0, x = 1 and y = 1 are

Question

$\begin {array} {1 1} (A)\;y = x, y + x = 1 & \quad (B)\;y = x, x + y = 2 \\ (C)\;2y = x, y + x =\large\frac{1}{3} & \quad (D)\;y = 2x, y + 2x = 1 \end {array}$