Aresearcher matched 30 participants on intelligence (hence 15 pairs of participants), and then compared differences in emotional responsiveness to two experimental stimuli between each pair. for this test, what are the critical values, assuming a two-tailed test at a 0.05 level of significance?

(a) ±2.042
(b) ±2.045
(c) ±2.131
(d) ±2.145