Which of the following sets represents the domain of the function shown? {(2, 3), (4, 7), (5, 9), (11, 6)}

Select one:

a. {2, 4, 5, 11}

b. {3, 7, 6, 9}

c. {(3, 2), (7, 4), (9, 5), (6, 11)}

d. {2, 3, 4, 5, 6, 7, 11}