Which word DOES NOT follow the same plural rule applied to ...

Confluence of Cultures

        A professional involved in a merchant marine career gets to meet and mingle with people of different cultures and nationalities. This helps the individual to understand and function better as a team player and learn the nuances of different cultures and traditions at the same time. This automatically increases adaptability and brings about more awareness about what goes and what doesn't in a different country.

(From: https://www .marineinsi ght. com/careers-2/10-reasonswhy-a-career-in-merchant-navy-ís-unl ike-any-other-career/)