A piece of wood from a recently cut tree shows 20 decays per minute .A wooden piece of same size placed in a museum (obtained from a tree cut many years back) show 2 decays per minute .If half life of $\;C^{14}\;$ is 5730 years , then age of the wooden piece placed in the museum is approximately :

Question

$(a)\;10439\;years\qquad(b)\;13094\;years\qquad(c)\;19039\;years\qquad(d)\;39049\;years$