Grassy i think is the answer if you were asking for the Adjective in "grassy slope" it'd be grassy
B. Adverbs describe verbs (things that are actions). Being tall isn't something the basketball player is doing, it is a description of them as a person.
My guess would be d. previously, because it's talking about early cars.
The chemicals had caused the eruption of smoke that filled the air. (Not sure if this is 100%)
