Half-life comparison substance a substance b substance c original amount 200 g 400 g 500 g ½ life 6 days 5 days 3 days from the table of data, substance c will have the least of the original amount remaining after 30 days even though it started with the most. what is the best explanation for this answer? a) substances a and b are not as radioactive since they have longer half-lives. b) the states of matter for substances a & b are more volatile than substance c. c) substances that start with large amounts will always decay at faster rates. d) substance c goes through a significantly larger amount of half-lives compared to the other substances.