Which of the following phrases defines the nature of the 'Hundi' generally referred to in the sources of the post-Harsha period?

A Hundi is a bill of exchange used in medieval India as a financial instrument for credit transactions and the safe transfer of money between merchants without the physical movement of cash. While options (a) and (d) are tempting as they describe official decrees, they are incorrect because a Hundi was strictly a commercial document rather than an administrative or feudal order. The core concept being tested is the evolution of trade, commerce, and financial practices in the post-Harsha and medieval periods.