C. The difference in the prices of gold and platinum ornament became very narrow and wearing platinum ornaments has become a fashion now.
Feedback We need to find a possible reason for people shifting from gold ornaments to platinum ornaments.
Choice (a) and (b) talk about prices of gold and platinum ornaments individually, but does not make any comparison between their prices.
Choice (c) states that the prices of gold and platinum ornaments is almost equal and wearing platinum ornaments is more fashionable than wearing gold ornaments. This is a possible reason why people prefer platinum ornaments to those of gold.
Choice (d) deters people from preferring platinum ornaments.
Hence, (c) is a possible cause.