The diagram represents a child X with mass $20\,\text{kg}$ and a child Y with mass $15\,\text{kg}$ sitting on a uniform plank. The plank has a mass of $7.0\,\text{kg}$ and a pivot located at its midpoint. The plank is horizontal and is in equilibrium. Which statement about the weight of the plank is correct?
- AThe weight of the plank can be considered to be acting at its midpoint.
- BThe weight of the plank is causing an anticlockwise moment.
- CThe weight of the plank is causing a clockwise moment.
- DThe weight of the plank equals the force on the plank from the pivot.