Final answer:
A 3 x 3 ANOVA would have 9 treatment groups because it is a two-factor ANOVA with each factor having 3 levels, creating 3 times 3 possible combinations.
Step-by-step explanation:
A 3 x 3 ANOVA would have 9 treatment groups. This type of factorial ANOVA is called a two-factor ANOVA because it involves two different independent variables (factors). Each factor has three levels, and every possible combination of the levels of the two factors is included, which results in 3 (levels for the first factor) x 3 (levels for the second factor) = 9 treatment groups.
Therefore, the correct answer to the question is (3) 9 treatment groups.