The generic form a+b -> ab is for a reaction, and ax + by -> ay +bx is for a - reaction

The first reaction, A + B --> AB is a combination reaction, where two individual reactants combine to form a single product.

The second reaction, AX + BY --> AY + BX is a double displacement reaction, where the two reactants each have two ions/units, and these are swapped, where the X transfers from A to B, and the Y transfers from B to A.

Sorry i think the answer is b

Firstly, the water in the dams hold gravitational potential energy as they are above ground level. the gravitational potential energy is then transferred to kinetic energy as it falls, spinning the turbinethe turbine then spins the generator, which is a large magnet surrounded by metal coils. by doing this, the generator generates electricity. in this action, the energy transfer taken place is kinetic to electric energy