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:Varying the TE makes it possible to probe compartment-specific T2 (whose decay Ferizi et al. (2015) finds to be monoexponential at the voxel level), an investigation which would be impossible with a single TE.
Category: