A radioactive nucleus A with a half life T, decays into a nucleus B. At t = 0, there is no nucleus B. At sometime t, the ratio of the number of B to that of A is 0.3. Then, t is given by :

Question

( A ) $t = \frac{T}{ \log 1.3}$
( B ) $t = \frac{T}{2} \frac{\log 2}{ \log 1.3}$
( C ) $t =T \frac{\log 1.3}{ \log 2}$
( D ) $t = T \log (1.3)$