Answer:
0.906
Explanation:
Let g = 9.81 m/s2. We can calculate the rate of change in potential energy when m = 201kg of water is falling down a distance of h = 131m per second

So the efficiency of the water turbine is the ratio of output power over input power:

Here, We know, Density = Mass / Volume
Here, mass = 249.8 g
volume = 92.5 cm³
Substitute their values,
d = 249.8 / 92.5
d = 2.7 g/cm³
In short, Your Answer would be "Aluminum"
Hope this helps!
I think the answer is C. Remaining constant