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:The oceans are currently the most extensively explored biome in regards to phage–bacteria interactions.(3) Studies based on prophage induction by DNA-damaging agents suggest that lytic infections are more common in high nutrient availability conditions, whereas lysogeny is more frequent in oligotrophic conditions.
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