All of the Following Are True of a Radionuclide Effective

All of the following are true of a radionuclide effective half-life EXCEPT:

A) It takes into account the relationship between physical and biologic half-lives.
B) It is the product of the physical and biologic half-lives divided by the sum of the physical and biologic half-lives.
C) It is always shorter than either the physical half-life or biologic half-life.
D) It is of little importance as a consideration of radionuclides used for medical diagnosis.