Which option correctly punctuates the following statement? "Optimal-level theories of motivation follow a homeostatic model. Opponent-process theories were advanced to account for addiction and other phenomena."

The first option is appropriate because the original statement is composed of two independent clauses that are each complete sentences and are effectively separated by a period. This punctuation is used correctly to maintain clarity and to signal the end of one thought before introducing another.

Choosing to leave the statement as is reflects adherence to standard punctuation conventions in formal writing, specifically within APA style, which values clarity and the integrity of separate ideas. The two clauses pertain to different aspects of motivation theories: the first discusses optimal-level theories, while the second introduces opponent-process theories. Keeping these as distinct sentences helps emphasize the individual ideas.

The other options attempt to connect the two clauses with different punctuation methods, which may not convey the intended emphasis or clarity. Using a comma, for example, could improperly create a run-on sentence. The dash introduces a pause that implies a relationship that may not be appropriate given the context. By using a semicolon, while grammatically correct in connecting related independent clauses, it alters the impact of how the information is delivered. Thus, the first option preserves the intended structure and clarity, making it the most effective choice.