If the decay or disintegration constant of a radioactive substance is\[\beta \], then its half life and mean life are respectively [IIT 1989; MNR 1990; MP PET 1995, 97, 99, 2002; MP PMT 1999, 2002; UPSEAT 2002]

• A.            \[\begin{matrix}    1  \\    \lambda   \\ \end{matrix}\] and \[\frac{{{\log }_{e}}2}{\lambda }\]     
• B.            \[\frac{{{\log }_{e}}2}{\lambda }\]and \[\begin{matrix}    1  \\    \lambda   \\ \end{matrix}\]
• C.            \[\lambda \ {{\log }_{e}}2\]and\[\begin{matrix}    1  \\    \lambda   \\ \end{matrix}\]                               
• D.            \[\begin{matrix}    \lambda   \\    {{\log }_{e}}2  \\ \end{matrix}\] and \[\begin{matrix}    1  \\    \lambda   \\ \end{matrix}\] (loge 2 can be written as ln 2)