The correct answer is - B. It measures the tendency of a radioisotope to decay radioactively.
Explanation:
The half-life of the radioactive sample is the time it takes to decay to its half amount of the unstable nuclei of its initial amount. It is radioactively decays to its half value or in simple words, it takes the time to decay an unstable nuclei to decay to its half value.
It can take milliseconds to million years to disintegrate the different unstable nuclei of a radioactive substance to disintegrate its half amount to a stable substance.
The more acidic the substance is, the more the iron nails will corrode (this obviously depends on what your experiment is but hope this helped in some way)
