ERa_NoCredit

=The Benchmark Assessment asked this:= An Upper Merion teacher was once quarantined during a medical procedure, because she was temporarily radioactive. Which accounts for her radioactivity?


 * A: She was exposed to intense gamma rays, which made her carbon-12 into radioactive carbon-14.
 * B: She ingested radioactive medicine, and radioactive isotopes collected in her thyroid gland.
 * C: She received high doses of x-rays, which remained in her body for an extended time.
 * D: Wait! Every one of these answers could explain why she was radioactive!

Concisely explain why the right answer was right, and why the wrong answers were wrong.

=The Following Answers Were Awarded No Credit. Can you tell why?=