Answer
Click the third graph (check the picture attached)
Step-by-step explanation
Remember that
, so the line in the first part of the graph means that the man is driving his car at certain speed (different form zero) from home to the store. The horizontal graph in the middle of the graph means that he man is sopping at the store; therefore his driving speed is 0. The third part of the graph means that the man is driving again from the store to home.
Check the picture bellow to visualize it more easily.