Given: The line y = x + 1 is a tangent to the curve y2=4x As we know that, the equation of tangent to the parabola y2=4ax at the point (x1,y1) is given by : y.y1=2a.(x+x1) Let (1, -2) be the point of contact ⇒−2y=4⋅(x+1) ⇒y=−2(x+1) So, when (1, -2) is the point of contact the equation of tangent to the given curve is y = - 2 (x + 1) But as we know that, equation of the tangent to the given curve is y = x + 1 So, (1,- 2) is not the point at which the line y = x + 1 is a tangent to the curve y2=4x. Similarly, let us suppose (1, 2) be the point of contact ⇒2y=4⋅(x+1) ⇒y=2⋅(x+1) So, when (1, 2) is the point of contact the equation of tangent to the given curve is y=2(x+1) But as we know that, equation of the tangent to the given curve is y=x+1 So, (1, 2) is not the point at which the line y = x + 1 is a tangent to the curve y=4x . Hence, option D is the correct answer.