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.