NZ Exporter enters CIF (Port of Destination) contract with US Importer. USI agrees to procure US Bank to issue a credit for benefit of NZE with NZ confirming bank. USB issues credit and requests NZB be confirming bank. USB undertakes to honour credit if bill of lading, commercial invoice, and policy of marine insurance presented. USB undertakes to honour credit if NZB dishonours. NZE presents conforming documents to NZB, but it dishonours. A: NZB is liable for dishonouring credit. B: USB is liable for NZB dishonouring credit