A Study Was Conducted to Test the Effectiveness of Supermarket

A study was conducted to test the effectiveness of supermarket sales strategies. At one supermarket, the price level (regular, reduced price, and at cost to supermarket) and display level (normal display space, normal display space plus end-of-aisle display, and twice the normal display space) were tested to determine if they had any effect on the weekly sales of a particular supermarket product. Each of the combinations of price level and display level were put in place for a randomly selected week and the weekly sales of the product was recorded. Each combination was used three times over the course of the experiment. The results of the study are shown here:

$\begin{array}{llcc}\text { The ANOVA table is shown below: }\\\begin{array} { l | c | c | c | c | c } \text { Source } & \text { DF } & \text { SS } & \text { MS } & \text { F } & \mathrm { P } \\\hline \text { Display } & 2 & 1691393 & 845696 & 1709.37 & 0.0000 \\\text { Price } & 2 & 3089054 & 154427 & 3121.89 & 0.0000 \\\text { Display*Price } & 4 & 510705 & 127676 & 258.07 & 0.0000 \\\text { Error } & 18 & 8905 & 495 & & \\\text { Total } & 26 & 5300057 & & &\end{array}\end{array}$ Which of the following tests should be conducted first?

A) A test of the Display Main Effect.
B) A test of the Weekly Sales Main Effect.
C) A test of the Price Main Effect.
D) A test of the interaction between Price and Display.