Which is the adjectival phrase in the sentence?

those old patio chairs on the deck are beginning to rust.

a.
on the deck

b.
patio chairs

c.
those old

d.
beginning to rust

An adjectival phrase or adjective phrase consists of a group of words that describes a noun or a pronoun. In the given sentence, the adjective phrase is, option C. Those old. The noun it describes is, "Patio Chairs".