Answer:
A
Explanation:
In one hour Marty walked three miles..He then stayed there because the line didn't move. If he had walked three more miles, the graph would have been moving up and instead of a horizontal line it would have been a diagonal line .
How you know he came home after 4 hours because right at five hours the line went down to 0 miles from his home. Which means he was at his home.
I hope this helps!