Answer
The correct answer is:
$(b) ~2$
Work Step by Step
The torque is $\tau = r\times F$, where $r$ is the smallest distance between the force vector and the axis, and $F$ is the perpendicular component of the force vector.
Vector 1 and vector 4 have similar magnitudes of force with vector 2, but $r_1$ and $r_4$ are both very small. Therefore, vector 1 and vector 4 produce smaller magnitudes of torque than vector 2.
Although vector 3 has a larger magnitude of force, the smallest distance $r_3$ between this force vector and the axis is very small, so the magnitude of the torque is very small.
The correct answer is:
$(b) ~2$
