For a radioactive isotope, the number of undecayed nuclei after an elapsed time t is related to the initial number N0 by N=N0e−λt, where λ is the decay constant. Which expression gives t in terms of N0, N, and λ?
a) λln(NN0)
b) λN0−N
c) λ1ln(NN0)
d) λ1ln(N0N)