C is the correct answer :))
Answer:
Is this a question for school or are you just asking normally?
Answer: the world woul become a <u>better</u> and a <u>more peaceful</u> place with a single.
Explanation:
Most of the time the definite article is used when we use superlatives like the best, the most dramatic, the most interesting, etc and a compartative is commonly used after a definite article like a more interesting plot or a clearer message, etc.
