Half life period of two elements are 40 minute and 20 minute respectively, then after 80 minute ratio of the remaining nuclei will be (Initially both have equal active nuclei) :

Question

$\begin{array}{1 1} (1)\; 4 : 1 \\ (b)\; 1 : 2 \\ (c)\; 8 : 1 \\ (d)\; 16 : 1 \end{array}$