The correct answer is: A) Mandu
Mandu was a major center of trade during the Malwa Sultanate period. It was located on the trade route between Gujarat and Delhi, and was a major producer of textiles, spices, and other goods. The city was also home to a number of important religious and cultural institutions, which made it a major destination for pilgrims and scholars.
Ujjain, Gwalior, and Chanderi were also important cities during the Malwa Sultanate period, but they were not as major centers of trade as Mandu. Ujjain was a religious and cultural center, while Gwalior and Chanderi were military strongholds.
Mandu was founded in the 10th century by the Parmar Rajputs. It was later conquered by the Delhi Sultanate in the 13th century, and then by the Malwa Sultanate in the 14th century. The city reached its peak under the rule of the Khalji dynasty in the 15th century. Mandu was abandoned in the 16th century after the Mughal conquest of Malwa.
Today, Mandu is a popular tourist destination. The city is home to a number of well-preserved monuments, including the Jami Masjid, the Hoshang Shah Tomb, and the Sher Shah Palace.