Here's why:
* Becquerel (Bq): This unit measures the activity of a radioactive source, which is the number of nuclear decays (emissions of radiation) that occur per second.
Let's look at the other options and why they are not correct:
* Gray (Gy): This unit measures the absorbed dose of radiation, which is the amount of energy deposited in a material by ionizing radiation per unit mass.
* Sievert (Sv): This unit measures the equivalent dose of radiation, which accounts for the biological effects of different types of radiation.
* Curie (Ci): This is an older unit of radioactivity, but it is still sometimes used. One Curie is equal to 3.7 x 10^10 Bq.
Therefore, the answer is Becquerel (Bq).
