Choose the One Alternative That Best Completes the Statement or Answers

Multiple Choice

Choose the one alternative that best completes the statement or answers the question.
-In the formula $\mathrm { A } ( \mathrm { t } ) = \mathrm { A } _ { 0 } \mathrm { e } ^ { \mathrm { kt } } , \mathrm { A }$ is the amount of radioactive material remaining from an initial amount $\mathrm { A } _ { 0 }$ at a given time $\mathrm { t }$ , and $\mathrm { k }$ is a negative constant determined by the nature of the material A certain radioactive isotope decays at a rate of $0.25 \%$ annually. Determine the half-life of this isotope, to the nearest year.

A) $3 \mathrm { yr }$
B) $277 \mathrm { yr }$
C) $120 \mathrm { yr }$
D) $200 \mathrm { yr }$