Write the Word or Phrase That Best Completes Each Statement $A ( t ) = 200 \mathrm { e } ^ { - .048 t }$

Multiple Choice

Write the word or phrase that best completes each statement or answers the question.
-A sample of 200 grams of radioactive substance decays according to the function $A ( t ) = 200 \mathrm { e } ^ { - .048 t }$ , 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) $0 \mathrm {~g}$
B) $77 \mathrm {~g}$
C) $423 \mathrm {~g}$
D) $1 \mathrm {~g}$