How is the sort order in which total models collect their values specified?
A. The sort order is specified in the admin configuration under Sales > "Checkout Totals Sort Order".
B. The sort order is specified in the system configuration under global/sales/quote/totals/ [total_code] with <before>and <after> nodes.
C. The sort order is defined by the module loading order as specified by the children of the modules/ [module_name]/depends configuration node.
D. The sort order is specified by the collect method in each total model.