Respuesta :
It's B. Barking is usually a verb, an action, but here, we're saying it like an adjective for the dog, "The barking dog".
The best description for the underlined word in this sentence is B) Barking is a verb form being used as an adjective to modify the dog.
Some verb forms can function in a sentence as adjectives modifying a noun. In this sentence, the word barking is the present participle form of the verb bark, functioning as an adjective since it is describing the dog.