Answer:
D. the object of the sentence.
Explanation:
Common nouns mention or describe general, non-specific terms for a person, place, thing, or idea. For example:
-People: mother, father, baby, child, etc.
-Animals: lion, dog, cat, bird, wolf, frog, etc.
-Things: table, bed, etc.
Usually, common nouns are not capitalized unless they begin a sentence.
Therefore, 'frog' is a common noun.
