Six Second Grade Students Tried Tossing a Ball into a Basket

Multiple Choice

Six second grade students tried tossing a ball into a basket ten times each. Their teacher tl suggested a different way of tossing the ball, and the six students tried again. The numbe successful tosses, before and after the teacher's suggestion, are shown below.
$\begin{array}{c|cccccc}\text { Student } & \text { A } & \text { B } & \text { C } & \text { D } & \text { E } & \text { F } \\\hline \text { Before the suggestion (out of 10) } & 5 & 3 & 5 & 4 & 5 & 3 \\\text { After the suggestion (out of 10) } & 2 & 3 & 2 & 6 & 2 & 3\end{array}$

Find the positive rank sum. [Recall, differences of zero are not ranked.]

A) +3
B) +9
C) +15
D) +1