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:We hypothesize that our observations can be explained by the fact that inactivated X chromosomes can be reactivated as the result of ageing and decreased levels of 5-methyldeoxycytidine (Wareham et al 1987; Wilson et al 1987).
Category: