In a radioactive sample. `._(19)^(40)K` nuclei either decay into stable `._(20)^(40)Ca` nuclei with decay constant `4.5 xx 10^(-10)` per year or into stable `._(18)^(40)Ar` nuclei with decay constant `0.5 xx 10^(-10)` per year. Given that in this sample all the stable `._(20)^(40)Ca and ._(18)^(40)Ar` nuclei are produced by the `._(19)^(40)K` nuclei only. In time `t xx 10^9` years. If the ratio of the sum of stable `._(20)^(40)Ca` and `._(18)^(40)Ar` nuclei to the radioactive `._(19)^(40)K` nuclei is 99. The value of t will be. [Given : In 10 = 2.3]

Options

A. `1.15`
B. `9.2`
C. `4.6`
D. `2.3`

Answer

B