The chart shows rate of decay. A 3 column table with 7 rows. The first column is Half-lives elapsed, with entries 0, 1, 2, 3, 4, 5, 6. Second column is Fraction remaining, with entries StartFraction 1 over 1 EndFraction, StartFraction 1 over 2 EndFraction, StartFraction 1 over 4 EndFraction, StartFraction 1 over 8 EndFraction, StartFraction 1 over 16 EndFraction, StartFraction 1 over 32 EndFraction, StartFraction 1 over 64 EndFraction. Third column is Perentage remaining, with entries 100, 50, 25, 12.5, 6.25, 3.125, 1.563. Which value is being measured in the columns labeled "Fraction remaining” and "Percentage remaining”? years of decay quantity of energy number of stable atoms amount of material that has not decayed