A metal plate with a horizontal surface area of $0.50\text{ m}^2$ is positioned on the lake bed at a depth of $40\text{ m}$. Take the density of water as $1000\text{ kg m}^{-3}$ and the gravitational field strength $g$ as $10\text{ N kg}^{-1}$. What downward force is exerted on the plate by the water?
- A$20\text{ kN}$
- B$80\text{ kN}$
- C$200\text{ kN}$
- D$800\text{ kN}$