Ten Subjects Were Weighed Before and After a New Diet

Ten subjects were weighed before and after a new diet. The results were as as follows.
$\begin{array}{l|cccccccccc}\text { Subject } & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 10 \\\hline \text { Before } & 168 & 180 & 153 & 197 & 203 & 171 & 192 & 195 & 221 & 181 \\\text { After } & 152 & 163 & 137 & 210 & 210 & 171 & 181 & 190 & 221 & 189\end{array}$

a) Compute the test statistic
b) Can you conclude that the median weight differs before and after the diet? Use the $\alpha = 0.05$ level of significance.

A) a) $\mathrm { S } = 11$
b) We can conclude that the weights before and after the diet are different.
B) a) $\mathrm { S } = 10$
b) We can conclude that the weights before and after the diet are different.
C) a) $\mathrm { S } = 11$
b) We can not conclude that the weights before and after the diet are different.
D) a) $\mathrm { S } = 10$
b) We can not conclude that the weights before and after the diet are different.