'Woven' is used as an adjective in this sentence (meaning made by interlacing threads or strips of material) to qualify the noun phrase 'pashmina shawls'. An adjective can be modified by an adverb only. Among the highlighted words, 'intricately' is an adverb, and it aptly modifies the word 'woven', giving the meaning 'woven in a detailed manner'.
By interchanging (A) and (B), the sentence implies that for centuries, the expensive but exquisite, and intricately woven pashmina shawls were either party wear or the rare collections found in the wardrobes of the elite.
Hence, option b) is correct.