The right answer is B
A radiotracer is an entity composed of a carrier molecule and a detectable radioactive isotope using devices such as gamma cameras or positron emission tomography.
A radiotracer is either a radioactive isotope alone or the combination of a molecule and a radioactive isotope. In this case, it is said that the molecule is labeled by the radioactive isotope.
A radioactive isotope is an atom whose nucleus, unstable, emits radiation. It could be :
- alpha radiation consisting of two protons and two neutrons.
- a beta radiation consisting of a negative electron (beta) or a positive electron (beta +, positron).
- a gamma radiation consisting of a high energy photon.
