Option d is the correct answer. The Tughluq dynasty ruled over the Delhi Sultanate for the longest period of 94 years from 1320 to 141 Following the invasion of South Asia by the Ghurid dynasty, five largely unrelated dynasties ruled over the Delhi Sultanate sequentially: The Mamluk dynasty (1206-1290, 84 years), The Khalji dynasty (1290-1320, 40 years), The Tughlaq dynasty (1320-1414, 94 years), The Sayyid dynasty (1414-1451, 37 years), and The Lodi dynasty (1451-1526, 75 years).