ANSWER
(a) -3, 3
(b) 0
Step-by-step explanation
The local minima are the "valleys" of the function. A function can have valleys and hills - the hills are the maxima.
In this function we can see two valleys and one hill. The minima are at the values x = -3 and x = 3, and the value of the function at those points is 0 for both.