Tidal study

 Which of the following demonstrates correct punctuation?

 We will study three sources of electrical power; solar, wind, and tidal energy.

 We will be studying three sources of electrical power, solar, wind, and tidal energy.

 We will be studying three sources of electrical power: solar, wind, and tidal energy.

 We will study three sources of electrical power that are: solar, wind, and tidal energy.

Correct

Answer:

We will be studying three sources of electrical power: solar, wind, and tidal energy 

When adding a list that gives the details of a claim in the sentence, use a colon. The colon must follow an independent clause. In other words, the part in front of the colon should be able to stand on its own as a sentence. “Will study/will be studying” are both grammatically correct and do not affect the solution.

We will study three sources of electrical power that are: solar, wind, and tidal energy is incorrect because the part of the sentence in front of the colon cannot stand on its own. “That are” leaves the sentence with an incomplete idea.

We will study three sources of electrical power; solar, wind, and tidal energy is incorrect because a semicolon needs to divide two independent clauses, and the portion following the semicolon has no verb. 

We will be studying three sources of electrical power, solar, wind, and tidal energy is incorrect because a comma turns “electrical power” into one item of a list of nouns joined by “and.” The sentence implies that “we” will be studying three sources of electrical power, three sources of solar, three sources of wind, and three sources of tidal energy.