Chapter 11 - Rotational Dynamics and Static Equilibrium - Problems and Conceptual Exercises - Page 375: 118

$(A) 0.0023N.m $

We know that $\Sigma \vec{\tau}=F_2(D-d)$ We plug in the known values to obtain: $\Sigma \vec{\tau}=(1.8N)(4.5\times 10^{-3}m-3.2\times 10^{-3}m)$ $\Sigma \vec{\tau}=0.0023N.m$ Thus, the correct option is (A).