Mystery Star 5 is the oldest. I know this because the data from data table 2 helped me determine my answer because it showed that Mystery Star 5 had the highest concentration of isotopes that decay slowly over time.
The radiometric dating data shows that Mystery Star 5 has the oldest estimated age of 4.6 billion years, which means it has been around since the formation of the solar system. This is supported by the presence of certain stable isotopes that have a long half-life, indicating a longer time frame for the accumulation of these isotopes compared to the other Mystery Stars.