Although I did get the answer right, I had to pick the closest response to the correct answer.
Technically, it was version 6.50.339 that fixed the Y2K issue. Then, Service Pack 5 came out (version 6.50.415) which was defective and you shouldn't have used it. Then, Service Pack 5a (version 6.50.416) released.
So, you could have fixed the Y2K problem before the release of SP5a if you installed the "Y2K" hot fix to the 6.50.281 (SP4) or 6.50.297 versions.