Write the equation of the quadratic that contains the points (-1, 0), (4, 0), and vertex (2, 6) in factored form.
a. y = (x + 1)(x - 4)
b. y = (x - 1)(x + 4)
c. y = (x + 1)(x + 4)
d. y = (x - 1)(x - 4)