Option 1 states that the Guptas ruled mainly over parts of north and central India. This statement is incorrect. The Guptas actually ruled over a vast empire that extended beyond just north and central India. They had control over a large portion of the Indian subcontinent, including present-day India, Bangladesh, and parts of Nepal. Their empire encompassed territories in the Gangetic plain, as well as regions in western and eastern India. Therefore, option 1 is the statement that is not true about the Guptas. It is important to note that the other statements in the options are true. Kingship in the Gupta empire was hereditary, the judicial system was more developed than in earlier times, and land taxes increased while taxes on trade and commerce decreased.