Final answer:
A proper noun is the best answer because it refers to a specific person, place, thing, or idea.
Step-by-step explanation:
The correct answer is A. proper noun. A proper noun is a specific name given to a person, place, thing, or idea. It always starts with a capital letter. For example, 'Paris' is a proper noun because it refers to a specific city, whereas 'city' is a common noun because it refers to a general category.
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