Writing and Reading

      [1] In addition to the baseline record, Turner also photographed the panels of prehistoric rock art in infrared wavelengths, yielding some surprising results. [2] Rock art pigments react differently in infrared wavelengths, which are invisible to the human eye, than they do in visible light. [3] The initial expectation was that lighter pigments, such as white, would become transparent, while darker colors, such as red, would become even darker, allowing the observer to see beneath a white outer layer of pigment to the darker image beneath. [4] This would help reveal vandalized or eroded red pigments that could no longer be seen with the naked eye. [5] What was discovered, however, is that rock art pigments don't always follow expectations.

To make this paragraph most logical, sentence 5 should be placed