Insurance adjusters are always vigilant about being overcharged for accident repairs. The adjusters suspect that Repair Shop 1 quotes higher estimates than Repair Shop 2. To check their suspicion, the adjusters randomly select 12 cars that were recently involved in an accident and then take each of the cars to both repair shops to obtain separate estimates of the cost to fix the vehicle. The estimates are given below in hundreds of dollars.

Car: 1 2 3 4 5 6 Shop 1: 21.2 25.2 39.0 11.3 15.0 18.1 Shop 2: 21.3 24.1 36.8 11.5 13.7 17.6 Car: 7 8 9 10 11 12 Shop 1: 25.3 23.2 12.4 42.6 27.6 12.9 Shop 2: 24.8 21.3 12.1 42.0 26.7 12.5 Assuming that the conditions for inference are reasonably met, which of the following significance tests could legitimately be used to determine whether the adjusters’ suspicion is correct?

(a) A paired t test

(b) A two-sample t test

(c) A t test to see if the slope of the population regression line is 0

(d) A chi-square test for homogeneity

(e) A two-sample z test for comparing two proportions