If an Isotope's Half-Life Is 100 Years

If an isotope's half-life is 100 years:

A) That isotope will no longer exist in 50 years
B) That isotope will no longer exist in 200 years
C) In 50 years only half of the atoms in a sample of that isotope will remain
D) In 100 years only half of the atoms in a sample of that isotope will remain
E) In 200 years only half of the atoms in a sample of that isotope will remain