5.67+42.4561 Now, I need help I dont even know what that means and its extra points!

Let the closed interval [a , b] be the domain of function f. the domain of f(x - 3) is given by (a) the open interval (a , b) (b) the closed interval [a , b] (c) the closed interval [a - 3 , b - 3] (d) the closed interval [a + 3 , b + 3]

Which equation represents the function on the graph?

In a column proof the right column states your reasons