5 different variably sized fragments of DNA upstream (5') of Human Gene Y, between +1 and -1500, were fused to the 5' end of a fragment of DNA encoding the Luciferase enzyme. The start of transcription is at +1, the root of the bent arrow. A scale is shown at top left. These reporter constructs were then transfected into a human cell line. Cytosol extracts were prepared 24 hours later and luciferase activity measured. The results are shown to the right for each construct. Which of the following segments of the 5' upstream sequence is most likely to contain an enhancer element.