Choose the One Alternative That Best Completes the Statement or Answers

Choose the one alternative that best completes the statement or answers the question.
-A sample of 650 grams of radioactive substance decays according to the function $\mathrm { A } ( \mathrm { t } ) = 650 \mathrm { e } ^ { - .038 \mathrm { t } }$ , where $t$ is the time in years. How much of the substance will be left in the sample after 20 years? Round your answer to the nearest whole gram.

A) $304 \mathrm {~g}$
B) $294 \mathrm {~g}$
C) $1 \mathrm {~g}$
D) $0 \mathrm {~g}$