Power is defined as the rate at which work is done or energy is transferred. First, calculate the work done by the pump to lift the water. The work done against gravity is equal to the potential energy gained by the water. Work done ($W$) = $mgh$ Given: Mass ($m$) = 500 kg Height ($h$) = 20 m Acceleration due to gravity ($g$) = $10 \ m/s^2$ $W = 500 \times 10 \times 20 = 100000 \ J$. Next, calculate the power using the formula: Power ($P$) = $\frac{Work \ done}{Time}$ Given: Time ($t$) = 10 s $P = \frac{100000 \ J}{10 \ s} = 10000 \ W$. Therefore, the power of the pump is 10000 W. Options A, B, and D are incorrect as they do not match the calculated power.