A BGP router should use three export policies named add-communities, no-rfc1918-routes, andrejected-unwanted. Which export statement places the add-communities policy immediately before the default BGP policy?（）

A、export [add-communities no-rfc1918-routes rejected-unwanted];

B、export [no-rfc1918-routes add-communities rejected-unwanted];

C、export [add-communities rejected-unwanted no-rfc1918-routes];

D、export [no-rfc1918-routes rejected-unwanted add-communities];