Find the critical value. Assume that the test is two-tailed and that $n$ denotes the number of pairs of data. $n=20, \alpha=0.01$ A. -0.570 B. \pm 0.570 c. 0.570 D. \pm 0.447

Step 1 ：Given that the test is two-tailed, the significance level \(\alpha = 0.01\) is divided by 2. So, we have \(\alpha/2 = 0.01/2 = 0.005\).

Step 2 ：We look up the value in the t-distribution table that corresponds to a tail probability of 0.005 and degrees of freedom \(df = n - 1 = 20 - 1 = 19\).

Step 3 ：The critical value from the t-distribution table is approximately \(\pm 2.861\).

Step 4 ：Therefore, the critical value is \(\boxed{\pm 2.861}\).