The half-life of a radioactive nuclide is `` 100 `` hours. The fraction of original activity that will remain after `` 150 `` hours would be :
(A) `` 1 / 2 ``
(B) `` \frac{1}{2 \sqrt{2}} ``
(C) `` \frac{2}{3} ``
(D) `` \frac{2}{3 \sqrt{2}} ``