A radioactive isotope emits alpha-radiation with an activity of 11.2 mCi and each particle having an energy of 8.49×10^–13 J. Assume a person weighing 65.5 kg is exposed to this radiation for 20.0 seconds and that 25.0% of the emitted alpha has been absorbed. Calculate the dose absorbed by the person in millirads and grays.

• A. 10.7 mrad; 1.07 Gy
• B. 10.7 mrad; 1.07×10^–4 Gy
• C. 2.69 mrad; 0.269 Gy
• D. 2.69 mrad; 2.69×10^–5 Gy