In this case, "down" is used in various grammatical forms:
- As a noun in option (1) in the context of "down" referring to a meal being consumed.
- As a verb in option (2) when it refers to the downward trend in the market.
- As an adjective in option (3) where "down" is used to describe the action of being sent to work.
- As an adverb in option (4) describing "the downs" in southern England.