Mary is using a one-sample t-test on the following group:Subject #15: 7.5 hoursSubject #27: 6 hoursSubject #48: 7 hoursSubject #80: 6.5 hoursSubject #91: 7.5 hoursSubject #82: 8 hoursSubject #23: 5.5 hoursSelect the two TRUE statements. a.)Mary would use the sample standard deviation to calculate a t-statistic. b.)Mary would use the population standard deviation to calculate a t-distribution. c.)The value for the degrees of freedom for Mary's sample population is six. d.)The t-distribution that Mary uses is taller than a standard distribution. e.)The t-distribution that Mary uses has skinnier tails than a standard distribution.