The sum of two polynomials is 8d⁵ - 3c³d² - 5c²d³ - 4cd⁴ + 9. If one addend is 2d⁵ - c³d² + 8cd⁴ + 1, what is the other addend?
a) 6d⁵ - 2c³d² - 5c²d³ - 12cd⁴
b) 6d⁵ - 4c³d² - 3c²d³ - 4cd⁴
c) 6d⁵ - 4c³d² - 5c²d³ - 12cd⁴
d) 8d⁵ - 2c³d² - 3c²d³ - 4cd⁴