Participants Rated Their Mood Score Out of 20 Before and After

Multiple Choice

Participants rated their mood score out of 20 before and after listening to Reign in Blood by the thrash metal band Slayer. $\begin{array} { | c | c | } \hline \text { Before Listening to Slayer } & \text { After Listening to } \mathbf { S l a y e r } \\\hline 5 & 14 \\\hline \mathbf { 8 } & \mathbf { 5 } \\\hline \mathbf { 9 } & 17 \\\hline 4 & 18 \\\hline \mathbf { 3 } & \mathbf { 8 } \\\hline 15 & 19 \\\hline 12 & 14 \\\hline \mathbf { 6 } & 16 \\\hline\end{array}$
- What is the null hypothesis of this study?

A) Listening to Slayer is no better than listening to no music at improving mood score.
B) Listening to Slayer does not affect mood.
C) Listening to Slayer increases mood score.
D) Listening to Slayer decreases mood score.