Parabola a can be represented using the equation (x + 3)2 = y, while line b can be represented using the equation y = mx + 9. isabel determines one solution to the system of two equations must always pass through the vertex of parabola a. which best describes the reasonableness of her solution? isabel is correct because the y-intercept of line b is (0, 9) and the value of y when x = 0 in parabola a is 9. isabel is correct because the y-intercept of line b is (9, 0) and the value of x when y = 0 in parabola a is 9. isabel is incorrect because the point of intersection between line b and parabola a that can be determined is the y-intercept of the functions, not necessarily the vertex. isabel is incorrect because the point of intersection between line b and parabola a that can be determined is the x-intercept of the functions, not necessarily the vertex.