The most likely clue for the word, "unity" as used in the section is C. "worked closely with the European Union, the United Kingdom, Japan, Canada, and New Zealand"
Unity refers to a state of multiple people or entities working together to achieve a certain goal.
Unity is therefore shown by the EU, UK, Japan, Canada, and New Zealand, working close together.
In conclusion, option C is correct.
Find out more on Unity at https://brainly.com/question/10763689.