Given below and the atomic masses of the elements: \begin{array}{|l|l|l|l|l|l|l|l|l|l|} \hline \text { Element: } & \mathrm{Li} & \mathrm{Na} & \mathrm{Cl} & \mathrm{~K} & \mathrm{Ca} & \mathrm{Br} & \mathrm{Sr} & \mathrm{I} & \mathrm{Ba} \\ \hline \text { Atomic Mas }\left(\mathrm{g} \mathrm{~mol}^{-1}\right): & 7 & 23 & 35.5 & 39 & 40 & 80 & 88 & 127 & 137 \\ \hline \end{array} Which of the following doesn't form triad?

• A

  $\mathrm{Ba}, \mathrm{Sr}, \mathrm{Ca}$
• B

  $\mathrm{Cl}, \mathrm{Br}, \mathrm{I}$
• Correct answer
  C

  $\mathrm{Cl}, \mathrm{K}, \mathrm{Ca}$
• D

  $\mathrm{Li}, \mathrm{Na}, \mathrm{K}$

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