Concept:For compound nouns like "editor-in-chief," only the main noun takes the plural form.
Explanation:The phrase "editor-in-chief" is a compound noun.
Its plural is formed by making the main word "editor" plural.
So, the correct plural is "editors-in-chief," not "editors-in-chief's" or "editor's-in-chief."
Among the options, only option C, "Editors-in-Chief," follows this rule.
Options A, B, and D are incorrect because they add extra plural endings or have spelling errors.
Answer:C. Editors-in-Chief