Tired, you were just look at the word after extremely and that would be your answer. For example you would say Dirty red shirt, So you would know that an adjective or something that describes the noun or object, So in the example I gave shirt is the object in the word before that is red which is describing the shirts so red would be the adjective and then the word before that would be the adverb if it like describes the shirt as well so dirty is describing how the shirt looks so dirty would be the adverb so your answer would be “tired”.