Find the critical value for $α = 0.10$ with $df = 18$ for a two tailed t-test.

$±1.734$

The correct answer is Option (2) → $±1.734$

Given $α = 0.10, df = 18$.

See area in right tail $\frac{α}{2}=\frac{0.10}{2}=0.05$ in topmost row against degree of freedom 18 in leftmost column. The critical value is 1.734.

Hence, the critical value for left tail is -1.734 and the critical value for right tail is +1.734.