Respuesta :
It's option A as half life can be called as the time required for a radioisotope to decay into a more stable isotope compared to its current state.
The rate at which a radioactive isotope decays is measured in half-life. The term half-life is defined as the time it takes for one-half of the atoms of a radioactive material to disintegrate. Half-lives for various radioisotopes can range from a few microseconds to billions of years.