When the Effect of a Level for One Factor Depends

Short Answer

When the effect of a level for one factor depends on which level of another factor is present, the most appropriate ANOVA design to use in this situation is the: $\begin{array}{|l|l|}\hline A.&\text {one-way ANOVA. }\\\hline B.&\text { two-way ANOVA.}\\\hline C.&\text {randomised block design. }\\\hline D.&\text {matched pairs design. }\\\hline \end{array}$