The image of the thin square metal plate showing the force and the lines are missing, so i have attached it.
Answer:
Line B represents the lever arm
Explanation:
From the attached image, we can see 4 different dashed lines between the force F and the moment centroid O.
Now, we want to know which of the dashed lines represents lever arm.
Now, in physics/engineering, the lever arm which is also known as moment arm is defined as the perpendicular distance between the line of action of the acting force and the centre of the moments.
Now, from the image attached, the only dashed line that is perpendicular to the acting Force F and the moment centre O is Line B.
Thus,line B represents the lever arm
