Answer:
The 4th list: Gregor, Isabelle, Juan, Karen, Hiroki.
Step-by-step explanation:
Times compared to personal best when arranged from most imporoved to least improved are:
+5.6, +3.2, 0, -5.2, -11.6
Now +5.6 is Gregors, +3.2 is Isebelle's, 0 is Jaun's, -5.2 is Karen's, and -11.6 is Hiroki's. Therefore, the list that orders runners from most improved to least improved is
Gregor, Isabelle, Juan, Karen, Hiroki
