In which order do you customize the electronic bank statement functionality?

In which order do you customize the electronic bank statement functionality?
A . "Create keys for posting rules.
Define posting rules.
Assign accounts to account symbols.
Assign bank accounts to transaction type."
B . "Create account symbols.
Assign accounts to account symbol.
Create keys for posting rules.
Define posting rules."
C . "Assign accounts to account symbols.
Assign interpretation algorithm to external transaction code.
Create keys for posting rules.
Assign bank accounts to transaction type."
D . "Create account symbols.
Assign external transaction types to posting rules.
Create keys for posting rules.
Create transaction type."