This soup has a spice that i cannot identify which kind of clause
a. noun
b. adjective clause or
c. adverb

The sentence This soup has a spice that I cannot identify contains a B. adjective clause.

Explanation:

Adjective clauses are dependent clauses used to modify a noun or pronoun. To do so, it will be introduced by a relative pronoun or subordinate conjunction. In this case, the adjective clause that I cannot identify is introduced by the relative pronoun that and modifiers the noun spice.