单选题 Silk, although it is considered a delicate fabric, is in fact very strong, but it is adversely affected by sunlight.

【正确答案】 C

【答案解析】delicate意为“娇弱的，纤细的；易碎的，脆弱的”，soft意为“软的”，sheer意为“完全的”，fragile意为“易碎的，脆的”，refined意为“精制的”。故答案为C。