Requirements for a Force Couple Steps:

• Recall that a couple consists of two equal, parallel forces in opposite directions acting along separate lines of action to produce pure rotation.
• Verify option A: opposite directions are essential for no net translation.
• Verify option B: same point of action would make forces concurrent, canceling as a single force, not a couple.
• Verify options C and D: equal magnitude and zero resultant force ensure torque without net force.

Why B is correct:

• A couple requires forces on distinct lines of action (per rigid body statics definition), so acting through the same point violates this by eliminating moment arm.

Why the others are wrong:

• A: Opposite directions are required to balance forces without net translation.
• C: Zero resultant force is necessary for pure torque, as per vector sum of forces.
• D: Equal magnitude ensures the forces cancel linearly while producing torque.

Final answer: B