Events A and B are defined by the sets {1, 2, 3, 4} and Events{3, 4, 5, 6}, respectively. What is the union of the two events? *
A. { 3,4 }
B. { 1,2,4,5 }
C. { 2,3,4,5,6 }
D. { 1,2,3,4,5,6 }.