Which technique would be best for bringing out the details of a bloody footprint?

Forensics uses special techniques to enhance the visibility of a bloody footprint. At times, a bloody footprint may not be visible to the naked eye. First, use ultra-violet light to detect bloody footprints in the area. Then, a chemical called Luminol can be used to create an impression of the bloody footprint.

C- a hypothesis or d- an observation

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