Question

Which of the following is the domain of the function { (3,6) , (5,7) , (7,7) , (8,9) } ?

A) {3,5,7,8}
B) {6,7,9}
C) { (6,3) , (7,5) , (7,7) , (9,8) }
D) {1,3,5,7,9}