Final answer:
The correct phrase to complete the sentence is 'sort out,' meaning to organize or resolve a problem, which in this context refers to addressing a mess.
Step-by-step explanation:
The correct phrase to complete the sentence “We need to … this mess” is “sort out.” The phrase “sort out” means to organize, resolve, or clarify a situation or problem, which fits into the context of dealing with a mess. Phrases like “bring up”, “find out”, and “lock up” have different meanings and would not be appropriate in this context.
“Bring up” is used when mentioning a subject or starting to discuss something. “Find out” means to discover or obtain information. Lastly, “lock up” is typically used to talk about searching for information, especially online or within a database. In the scenario provided, where a mess needs addressing, sort out is the correct term to use. It reflects the action of creating order from chaos and developing a plan to manage the situation effectively.
In relation to the provided reference text, sorting out a mess aligns with the need to face challenges and craft a plan that is rooted in the reality of the physical world. It emphasizes taking action and making decisions to improve a situation, much like formulating a credible global plan to deal with foundational global problems.