Which characteristic of nuclear power is described as a challenge due to uranium-235?

• A. It avoids any waste
• B. It produces no radioactive byproducts
• C. It is easy to store securely
• D. Disposal of nuclear waste remains a problem

Answer: (D)

The key idea is that nuclear power faces a long-term waste management challenge. When uranium-235 undergoes fission in a reactor, it releases energy but also creates highly radioactive byproducts and spent fuel that stay dangerous for thousands to millions of years. Safely isolating and containing this waste over such vast timescales, and finding permanent disposal solutions like deep geological repositories, is difficult and hasn't been universally resolved. That’s why the statement about disposal of nuclear waste remaining a problem best captures the main challenge.

For clarity: nuclear power does not avoid waste, and it does produce radioactive byproducts. It isn’t easy to store securely over the long term.