Given that -5i is a zero, factor the following polynomial function completely using the Conjugate Roots Theorem, if applicable.
f(x) = x⁴ + 11x³ + 49x² + 275x + 600
a) f(x) = (x + 5i)(x + 5)(x² + 6x + 20)
b) f(x) = (x + 5i)(x - 5)(x² + 6x - 20)
c) f(x) = (x - 5i)(x + 5)(x² + 6x + 20)
d) f(x) = (x - 5i)(x - 5)(x² + 6x - 20)