Multilayer food wrappers often contain polymer layers that cannot be recycled together. A research team tested a solvent that leaves each polymer intact while loosening the adhesive between layers. Microscopy showed the solvent entering along cut edges and spreading through the interfaces between layers, so the team predicted that increasing the total length of exposed cut edges—not merely stirring faster—would speed separation. Tests supported the prediction only until the pieces were about 2 millimeters across: further cuts did not speed separation, though faster stirring remained ineffective. This plateau admitted two explanations: solvent access to the interfaces had ceased to limit separation, or the tiniest pieces were clumping and thereby reducing the amount of edge accessible to the solvent. ______ microscopy of samples containing those pieces showed solvent along nearly every interface while the pieces remained dispersed.
Which choice completes the text with the most logical transition?
For a transitions question, identify not only the broad relationship between sentences but also the exact role of the new information. When one sentence presents competing explanations and the next supplies evidence that distinguishes between them, choose a transition emphasizing the evidence’s decisive significance rather than addition, exemplification, sequence, or simultaneity.
Hints
Track the two explanations
Determine what observation would support each explanation offered for the plateau.
Evaluate the role of the microscopy findings
Ask whether the final sentence merely adds an example or instead helps decide between the competing explanations.
Step-by-step Explanation
Identify the unresolved alternatives
The plateau could have occurred because solvent access was no longer limiting separation or because the smallest pieces were clumping and reducing the amount of exposed edge.
Determine what the final evidence establishes
Microscopy showed solvent along nearly every interface, supporting the first explanation. It also showed that the pieces remained dispersed, ruling out the clumping explanation.
Choose the precise relationship
The final finding is not merely another example or a simultaneous development; it is the evidence that distinguishes between the competing explanations. Therefore, the transition should emphasize the finding’s decisive importance.