Where does radioactivity come from?
a the decay of certain atomic nuclei
b the atom losing electrons
c radioactive material
d U-238

C. radioactive material

Explanation:

This exposure primarily comes from cosmic rays, radioactive material in the earth (such as uranium-238), ingestion of naturally occurring radionuclides in food (such as potassium- 40), and inhalation of radon gas. In the United States, the average background radiation dose is 300 mrem/yr.

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explanation: i will tell you how to if u answer my question.

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.