At a hydroelectric power station, $4.2 \times 10^5\,\text{kg}$ of water flows through the turbines each second. The turbines are positioned $50\,\text{m}$ below the surface of the reservoir. Take the gravitational field strength $g$ as $10\,\text{N kg}^{-1}$. If there are no energy losses, what is the power output of the power station?
- A$8.4 \times 10^3\,\text{W}$
- B$8.4 \times 10^4\,\text{W}$
- C$2.1 \times 10^7\,\text{W}$
- D$2.1 \times 10^8\,\text{W}$