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:…and overexpressors of circadian clock– related factors, including PRR5 and ZTL, are also affected in hypocotyl elongation during deetiolation (Sato et al., 2002;
(A) Five-day-old etiolated wild-type (Columbia [Col.]), ztl-3, and fkf1 seedlings were exposed to white light for 9 h and then…
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