Which of the following is most accurate in describing the problems of survivorship bias and backfill bias in the performance evaluation of hedge funds?
a. Survivorship bias and backfill bias both result in upwardly biased hedge fund index returns.
b. Survivorship bias and backfill bias both result in downwardly biased hedge fund index returns.
c. Survivorship bias results in upwardly biased hedge fund index returns, but backfill bias results in downwardly biased hedge fund index returns.