With reference to Medieval Indian History, what does 'Pietra Dura' refer to ? (A) It was a type of textile design prevalent in Deccan. (B) Coloured, hard stones placed in depressions carved into marble or sandstone creating beautiful, ornate patterns. (C) A variety of musical instrument played during Mughal wedding rituals. (D) A kind of coloured photograph brought from Iran to the Mughal court.