Which of the following is the solution set of 2a + 1 > 9 or a < –1?
a)

{a | a ≤ –1 or a ≥ 4}


b)

{a | –1 ≤ a ≤ 4}


c)

{a | a < –1 or a > 4}


d)

{a | a < –1 or a > 5}