Based on the Following ANOVA Summary Table (Fixed Effects) -For Which Source of Variation Is the Null Hypothesis Rejected

Multiple Choice

based on the following ANOVA summary table (fixed effects) :
$\begin{array}{cccc}\hline \text { Source } & d f & M S & F \\\hline \mathrm{A} & 5 & 18.0 & 6.0 \\\mathrm{~B} & 1 & 13.5 & 4.5 \\\mathrm{AB} & 5 & 15.0 & 5.0 \\\text { Within } & 60 & 3.0 & \\\hline\end{array}$
-For which source of variation is the null hypothesis rejected at the .05 level of significance?

A) A
B) B
C) AB
D) All of the above.