Hydro electric power is the process of production of electricity from the mechanical energy of water.
In the process of generation of hydro electricity ,large dams are constructed in which the water is stored.The water present at top of the dam has potential energy.The water is driven downward with high pressure. During the falling of water,the potential energy of the water is converted into equivalent kinetic energy. The water coming down with a heavy speed is allowed to fall on a turbine which is connected to a generator.
The mechanical energy of water drives the turbine and electricity is generated due to the electromagnetic induction .
Hence the option A is right i.e falling water that turns the turbine.
Answer:

Explanation:
Wien's displacement law states that the radiation of the black body curve for different temperatures will give peak values at different wavelengths and this wavelength is related inversely to the temperature.
Formally the law of Wien displacement states that the black body's spectral radiation per unit of wavelength, will give peaks at the wavelength of
which is given by the mathematical expression.
Here, b is proportionality constant with value of
The wavelength of the peak of the Gaussian curve is inversely related to temperature in degree kelvin.
<span>Water will diffuse down gradients of water potential, just as heat will flow down gradients of temperature and rocks will roll down gradients of gravitational potential</span>
Pressure and temperature are the variables in Gay-Lussac's law.
The law states that a pressure of a gas is directly proportional to the gas' temperature if the mass and volume are fixed. This means that there are only two variables, as the other two values are fixed: only pressure and temperature can change according to this law.