In a well-written paragraph, the explanatory sentences are appropriate responses to the sentence of the paragraph.
a. leading
b. topic
c. concluding
d. theoretical

The correct answer is B. Topic sentence. These are sentences found at the beginning of paragraphs and are basically what you're going to be talking in the paragraph. Explanatory sentences are used to support the topic sentence and topic sentences have to rely on previous paragraphs to make it coherent and cohesive.

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