3. What is the domain of the function below?
(-2,5)(-1,10)(4,5)(2,6)
A. D = {5, 6, 10
B. D = {-2,-1, 4, 2}
C. D = {-2,-1, 4, 2, 5, 10, 6}
D. D = {-1, 2,4}