Answer:
Intensive
Step-by-step explanation:
The options you were given are the following:
- intensive
- adjective
- noun
- empty word
- verb
The italicized word is extremely. It is an adverb. Adverbs are words used to modify verbs, adjectives, and other adverbs. Here, extremely modifies the adjective busy. This is why we can eliminate noun, adjective, and verb as potentially correct options.
Empty words are words that have no lexical meaning and function as a grammatical link or marker. An example of an empty word in English is the infinitive marker to.
Intensives are words used to show stronger, more forceful, or more concentrated actions. An example of an intensive used in English is so. Here, the word extremely intensifies the principal's busy-ness.