The correct option is A part-time
A compound adjective is formed when two or more adjectives are joined together to modify the same noun. These terms should be hyphenated to avoid confusion or ambiguity.
Option A: describes the type of work the worker does. The type of work is described in two words or two different adjectives "part" and "time". So this is the compound adjective
Option B: worker is a noun. He/she is the subject in the sentence.
Option C: Is also a noun, it is the object.
Option D: Yesterday is a pronoun which functions as a determiner.
Option A is the correct answer.