Correct answer is C.
Explanation: Chlorine is the 17th element in the periodic table that has an electronic configuration of 
![[Ne]3s^23p^5](https://img.qammunity.org/2019/formulas/chemistry/high-school/4hwjofwetiiiju8hlj98hs8an4c3qraui4.png) which has 1 electron less than the stable [Ar] gas and is very reactive in nature.
 which has 1 electron less than the stable [Ar] gas and is very reactive in nature.
Chlorine element is present in the form of gas that has a pungent odor and is highly toxic in nature. 
Option A, B and D are the ones which shows the actual property of the Chlorine, why we do not use pure chlorine but Option C is the only option that does not show the correct property of pure chlorine.