Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Recent technological advances have also enabled precision deep-water surveys with both remotely operated vehicles (ROVs) [Ballard et al., 2000; Whitcomb et al., 2000; Singh et al., 2000] and Autonomous Underwater Vehicles (AUVs) [e.
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