Last year, a random sample of 15 transactions showed a mean transaction value $45 with a standard deviation $5. This year, a random sample of 20 transactions showed a mean transaction value $55 with a standard deviation $10. Select the correct Excel add-in to get the p-value.

a) T test: Paired Two Sample for Means

b) Z test: Two Sample for Means

c) T test: Two Sample Assuming Equal Variances

d) T test: Two Sample Assuming Unequal Variances