Radioactive decay follows first order kinetics and the rate constant is often termed as decay constant. Certain radioactive substances may undero sequ

Radioactive decay follows first order kinetics and the rate constant is often termed as decay constant. Certain radioactive substances may undero sequential decays in order to convert into a stable nucleus. The series comprising all such elements is termed as radioactive disintegration series.
A substance A undergoes sequential decay as shown `A overset(lambda_(1))rarr B overset (lambda_(2))rarr C`. If the decay constant `lambda_(1)` and `lambda_(2)` are `4 xx10^(-2) "min"^(-1)` and `16 xx 10^(5) "min" ^(-1)` respectively then the molar ratio of B to A after a very long time will be :
A. `2.5 xx 10^(-8)`
B. `4 xx 10^(-2)`
C. `(1)/(16 )xx 10^(-5)`
D. `4 xx 10^(7)`