Option d is the correct answer. Gol Gumbaz is a 17th-century mausoleum in Bijapur, Karnataka, India, housing the remains of Mohammad Adil Shah, the seventh sultan of the Adil Shahi dynasty. It features a massive dome, about 44 m in external diameter, with unique interlocking pendentives. The dome's design is a prominent example of the southern regional style of IndoIslamic architecture and is renowned for being the largest dome in the Islamic world during its construction. The gallery around the dome, known as the 'whispering gallery,' reflects sound across the dome.