Which of the following statements must be true about the polynomial function f(x)?

a. lf 1 13 is a root of f(x), then-1- 13 is also a root of f(x)13i is also a root of f(x)

b. lf 1 13i is a root of f(x), then 1If 13 is a root of f(x), then -13 is also a root of f(x)O

c. lf -13 t i is a root of f(x), then 13 i is also a root of f(x).