[单选题]
A hypothetical radioactive substance 6 xn*7,3wixu3 f4uvn ttzwe ;aA.ge 7*fl lgue+aptinium decays via alpha-emission into Physicsbowlium. The decay constant for this alpha-emissiong7l ef* gleu+. is 20 $s^{-1}$.
12.42 What is the half-life of Aaptinium?
A. 0.035 s
B. 0.050s
C. 0.100 s
D. 0.297 s
E. 0.693 s