>>51
Of course there is. C can receive a copy of the binary via A, who can (at his whim) relicense it to not require an offer of source code to be distributed alongside the binary.
Perhaps you should read the actual text of the GNU GPL version 3, rather than relying on your personal hallucinatory memories of it. For a software license, it's very readable and its legalese is of the kind that can be understood by informed laymen.