A random sample of 30 executives from companies with assets over $1 million was selected and asked for their annual income and level of education. The ANOVA comparing the average income among three levels of education rejected the null hypothesis. The mean square error (MSE) was 243.7. The following table summarized the results:

	High School or less	Undergraduate	Masters or more
Sampled	7	11	12
Mean Salary (1,000's)	49	76.3	78.3

Based on the comparison between the mean annual incomes for executives with undergraduate and master's degrees or more, ______.

a. a confidence interval shows that the mean annual incomes are not significantly different

b the ANOVA results show that the mean annual incomes are significantly different

c. a confidence interval shows that the mean annual incomes are significantly different

d. the ANOVA results show that the mean annual incomes are not significantly different