Given a scientific question, generate a correct answer to it.
--------
Question: How long do the long-lived isotopes require to decay to a safe level in a nuclear reactor?

Answer: thousands of years

Question: G2 and s are phases in what process that is important in cell division?

Answer: mitosis

Question: The major classes of living members of this phylum include gastropods, bivalves, and cephalopods?

Answer:
mollusks