Answer: Hydroelectric power will be the best energy source.
Explanation:
Solar energy- It refers to the energy that is directly derived from the sun, and are later used to convert into some kind of electrical or thermal energy. For example, solar panels.
Biomass energy- It is a type of energy that are directly obtained from the plants as well as organisms. This can be regenerated again and again. For example, bio-gas and food crops.
Hydroelectric power- It is a type of energy that is collected, from the rapid motion of water. A dam is needed to construct across a narrow river, which will store water as a reservoir. And this water, when allowed to flow then it initiates the movement of the turbines and due to this continuous motion of the turbines, electricity is generated.
Thus, the most efficient energy source for the given area is the hydroelectric energy, that fulfills the condition for setting up dams in the two rivers, which will generate a huge amount of electricity.