Answer: tall
Step-by-step explanation:
The tall man is my uncle.
The is an article.
Tall man is my uncle.
Man is a noun.
Tall is my uncle.
Uncle is a subjective compliment.
Tall is my.
Is is a linking verb.
Tall my.
My is an adverb.
Tall.
Tall is left as the describing word, the adjective, therefore tall is the adjective.