Which Was the Most Successful of Diocletian's Economic Reforms

Which was the most successful of Diocletian's economic reforms?

A) Requiring the land tax to be paid in produce or goods rather than in the worthless coinage
B) Reissuing coins with copper
C) Issuing an edict setting a maximum cost of items
D) Issuing pure gold and silver coins to soldiers as donatives every five years
E) Making professions hereditary by law