Answer:
"Red" is the adjective.
Explanation:
As a reminder, an adjective is a word that describes a noun. "The dog rips the red sock" is a simple sentence, so let's break it down.
"The dog" is the noun here. It is the main character of this sentence.
"rips" is the verb. It describes what the dog is doing.
"red" is the adjective. It describes the sock.
"sock" is also a noun.
Since "red" is the only word describing another word, it is the adjective. Hope this helps!