7. BIM's test preparation software for the FAA IRA exam claims it will enable flight stu- dents to score above the national average, which is u=51.5 (o unknown). A researcher tests this claim by randomly selecting 100 flight students, having them prepare for the exam using BIM's software, and then taking the exam after preparing for it for 30 days. Based on the results, the researcher failed to reject Ho for a = .05. The reason for this decision is because

a. t critical >t statistic

b. t critical < t statistic

c. The sample mean was considered a highly improbable outcome.

d. The researcher used a one-tailed test to the right.