A. Load all country and statecombinations in a data table and write a Constraint rule to lookup the data table.

B. Use the Hiding rule, which is the only possible option, because arraysdo not do not support Constraint rules.

C. Create Hiding rules for each country with Simple Conditions, and then select valid states for the Action attribute. In this case, the number of Hiding rules will be equal to the number of countries.

D. Create a Constraint rule for each country in the drop-down list by using Simple Conditions and select valid states for the Action attribute of the rule. In this case, number of rules will be equal to the number of countries in the list.