Hi there!
1st question: answer: either AB, EF or FG
We were looking for a linear line that was decreasing. Therefore, we were looking for a straight line downwards in the graph. This can be AB, EF or FG.
2nd question: answer: EF.
The line EF is the line that decreases the fastest: the distance from home decreases in a short time, and therefore Miguel is travelling the fastest over there.