In a two-factor ANOVA, what is the implication of a significant AxB interaction?

In a two-factor ANOVA, what is the implication of a significant AxB interaction?
 
  A) At least one of the main effects must also be significant.
  B) Both of the main effects must also be significant.
  C) Neither of the two main effects can be significant.
  D) The significance of the interaction has no implications for the main effects.

Question 2

A jar contains 10 red marbles and 30 blue marbles. A random sample without replacement of n = 3 marbles is selected from the jar. If the first two marbles are both blue, what is the probability that the third marble will be red?
 
  A) 10/37
  B) 10/38
  C) 10/40
  D) 8/38

Question 3

In a two-factor ANOVA, which of the following is not computed directly but rather is found by subtraction?
 
  A) SSbetween treatments
  B) SSA
  C) SSB
  D) SSAxB

Question 4

A jar contains 10 red marbles and 30 blue marbles. What is the probability of randomly selecting a red marble from the jar?
 
  A) 10/30
  B) 10/40
  C) 1/10
  D) 1/40