(D. flashback) my good sir i give u the answer
She is proud her son met some one. i have no idea honey you need to put what book or excerpt it is from..
Answer: exposure
Explanation:
"To expose" is a verb that refers to putting someone at risk from something harmful. Exposure refers to the act of being exposed to something dangerous, such as radiation. So the best word to complete the sentence is "exposure":
Marie Curie conducted pioneering research on radioactivity and discovered the radioactive elements, not knowing how deadly exposure to radiation could be.