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A friend hypothesizes that hot water will cause a sugar cube to dissolve faster than cold water will. She investigates by filling three cups;one with hot water, one with cold water, and one with ice water. Which observation will help her decide whether her hypothesis was correct?
(A)which cup the sugar cube dissolves in first
(B)the time it takes for two sugar cubes to dissolve
(C)changes in water temperature from start to finish
(D)changes in the size of the sugar cube in cold water
which cup the sugar cube dissolves in first