Radioactive Decay: the Decay Rate of an Isotope Is Initially

Radioactive decay: The decay rate of an isotope is initially R₀, but after one half-life has gone by, the rate is R₀/2. At the end of the NEXT half-life, what will the decay rate be?

A) 0
B) R₀/16
C) R₀/e
D) R₀/4
E) R₀/e²