Hello!
A line of best fit usually shows the average, and usually cuts through the points, leaving about an even amount on both sides.
Graphs B and D are two far to one side of the points, and graph C doesn't correlate with the points at all.
In A, the line puts 6 points on both sides, so it is very even and represents the data very well,
So, our answer is the first graph.
I hope this helps!