Step 1 :The owner of a football team claims that the average attendance at games is over 523. A hypothesis test was conducted to verify this claim. The conclusion of the hypothesis test is a failure to reject the null hypothesis. In hypothesis testing, the null hypothesis is reject the null hypothesis means that there is usually a statement of no effect or no difference. In this case, the null hypothesis would be that the average attendance is not over 523. A failure to not sufficient evidence to support the claim that the mean attendance is greater than 523. Therefore, the final answer is \(\boxed{\text{D. There is not sufficient evidence to support the claim that the mean attendance is greater than 523.}}\)