Technetium-99m, with a half-life of about 6h, is widely used for diagnostic imaging in medicine. Which of the following best explains why an isotope with such a short half-life is preferred over a more stable isotope for this purpose?
a) Its short half-life means the nuclei emit lower-energy radiation, reducing the dose received by the patient.
b) Because the isotope decays completely within a day, no radioactive material remains in the body after the scan.
c) Its higher activity produces clear images while decaying away quickly, minimizing long-term radiation dose to the patient.
d) Isotopes with shorter half-lives are less likely to undergo γ emission, so they are inherently safer for diagnostic purposes.