Explain how to graph a piecewise function

 Just graph the function up to and/or including the points indicated. 

- if you have a piecewise function defined as y=x when x < 0 
y=-x when x >=1 

You would graph y=x from the negative direction up to 0 (but leaving an open circle on 0 because the function is not defined there 

Then start at point 1 (this time with a closed circle because y=-x is defined at 1, and graph y=-x.

The answer would be choice b