Passage Summary: Radioactive stuff doesn't last forever—it breaks down pretty quickly. If it all started at the beginning of time, it would be gone by now, but we still see plenty of it, so it must still be getting made.

Conclusion: Radioactive elements are currently being produced throughout the universe.

Reasoning: Since radioactive elements decay into nonradioactive ones within a few million years, they would have vanished by now if they were only created at the universe's inception; however, they remain abundant.

Analysis: This is a classic 'Identify the Conclusion' task where the main point is tucked into the middle of the stimulus. I identified it by looking for the author's primary claim, which is signaled by the contrast word 'However.' The sentences following that claim act as evidence, using a conditional 'if/then' structure to prove that the current abundance of these elements necessitates their ongoing creation. Focus on the structure: the author presents a possibility, rejects it with evidence, and asserts their own position as the takeaway.