`._(84)^(218)Po` `(t_(1//2) = 183 sec)` decay to `._(82)^(214)Pb` (`t_(1//2) = 161`) sec by `alpha` emission, while `._(82)^(214)Pb` decay by `beta`-emission. In how much time the number of nuclei of `._(82)^(214)Pb` will reach to the maximum?
A. 182 sec
B. 247.5 sec
C. 308 sec
D. 194.8 sec