Select the word from the list that best fits the definition

is measured in half-lives

remains
fossil
mold
hard
missing layer
trace
radioactive decay
cardon-14

The answer is:

radioactive decay

The reason for this definition is that it takes one-half of the atoms of a radioactive material to disintegrate.

radioactive decay

Explanation:

A radioactive decay is the phenomena in which an unstable nucleus of an atom get split into alpha, beta and gamma particles. The atomic nucleus looses energy in this process and emits radiations. The rate at which the unstable nucleus decays is called as half life. The half life is the time required for one half of the element to decay. Therefore, the radioactivity of the radioactive element can be measured in terms of half-lives.

i would go with b

cytokinesis occurs after telophase so that eliminates d

and the entire reason for cytokinesis is for cellular reproduction