Two radioactive samples $X$ and $Y$ have the same number of atoms initially $\left[N_X(t=0)\right.$ $\left.=N_Y(t=0)\right)$. The half life $\tau_{1 / 2}^x$ of $X$ is half the mean life of $Y$. Then the ratio $N_Y(t) / N_X(t)$ when $t=\tau_{1 / 2}^x$ is close to

• A

  $0.8$
• B

  $1.0$
• Correct answer
  C

  $1.2$
• D

  $1.4$

Hence, the correct answer is option: 'C'.