Which point is a distance of 5 units from the point (1,9)?
a.) (6,8)
b.) (2,4)
c.) (3,3)
d.) (5,6)
can someone explain how to find the answer?

You just need to plot them on a graph and see how many spaces are in between each.  So if you plot (1,9) remember it's X, Y axis.  Start from zero on the graph.  Since it's positive go over 1 to the right and up 9.  Then do the same for the rest. Then count how many units are between each point on the graph and find the one that is 5 units apart.