Jan'ai was asked to determine the minimum for a function with zeros located at -1 and 5, which also has a y-intercept of (0,25). Her work is shown.

Begin to write a function in factored form. f(x) = a(x+1)(x-5)
Substitute to determine a. -25 = a(0+1)(0-5)
Simplify and solve to find a. a=5
Rewrite the function. f(x) = 5(x+1)(x-5)
Rewrite in standard form. f(x) = 5x^2-20x-25
Find the x-coordinate of the vertex. x = -20/2(5) = -20/10; x = -2
Find the y-coordinate of the vertex. y = 5x^2-20x-25
y = 5(-2)^2-20(-2)-25
y = 35 so (-2,35)

Which best describes the first error in Jan'ai's work?

A) She incorrectly determined the factors for the beginning function.
B) She incorrectly determined the a value.
C) She incorrectly transformed the equation to standard form.
D) She incorrectly determined the x-coordinate of the vertex.