In the sentence "The dog barked loudly during the night," what does "loudly" modify?

In the sentence "The dog barked loudly during the night," the word "loudly" functions as an adverb, providing more information about how the dog barked. Adverbs typically modify verbs by describing the manner in which an action is performed, and in this case, "loudly" specifically modifies the verb "barked." It answers the question of how the barking occurred, indicating that it was done with a significant level of volume.

On the other hand, the other options do not fit this context: "dog" is a noun, "the night" is a noun phrase referring to a specific time, and "during" is a preposition that does not serve as the action but rather indicates a time frame. Therefore, "loudly" is appropriately linked to "barked" as it clarifies the way in which the barking happened.