The correct option is A with ginger hair
An adjective clause is a group of words that contain a subject and a
verb, and it functions as an adjective that modifies a noun or a
pronoun. Adjective clauses usually begin with relative pronouns such as
who, whom, whose or a relative adverb like when, where and so on.
An adjective phrase is a group of words (lacking a subject and a verb)
that performs the function of an adjective, i.e., it modifies a noun.
When
an adjective clause is reduced to a phrase, the relative pronoun is
removed, because it functions as the subject; and the verb is changed to
a present participle (verb + ing) or left out. When the sentence is in passive
voice, the verb is changed to past participle (verb + ed - generally).
Option A is correct as it is a prepositional phrase that functions as an adjective. The relative pronoun 'whose'
is removed and the verb form of 'to be', "is" is also removed.
(Prepositional phrases are of two kinds- adjective phrases and adverb
phrases. The former modifies a noun and the latter modifies a verb,
adjective or another adverb.)
Option B is incorrect because the words form an adverb phrase of place. Also, it is different in meaning from the underlined clause.
Option C is incorrect because when replaced, 'boy' is repeated twice: I met a boy gingered hair boy.
Option D is incorrect because the answer lies in A.