Two radioactive elements $A$ and $B$ initially have the same number of atoms. The half-life of $A$ is equal to the mean life of $B$. If $\lambda_A$ and $\lambda_B$ are the decay constants of $A$ and $B$ respectively,then choose the correct relation from the given options.

• A
  $\lambda_A = \lambda_B$
• B
  $\lambda_A = 2 \lambda_B$
• C
  $\lambda_A = \lambda_B \ln 2$
• D
  $\lambda_A \ln 2 = \lambda_B$