A disadvantage of Radix Sort is:

It needs auxilliary storage beyond the input array
  • It is not stable(i.e. records with equal-valued keys might not be in the same order in the output as they were in the input)
  • It is a quadratic time sort
  • None of these answers

Radix Sort is stable (otherwise, each digit's sort would mess up the previous digits).

Radix Sort's time requirements depend on the number of records and the number of digits. When implemented properly, the number of digits is no worse than the log of the number of records.

Radix Sort does need auxilliary storage.