The correct option is C A chemical with a pungent odour is added in LPG/CNG to detect leakage.
Any accidental leakage can cause an explosion. If the gas leaks in any closed space such as kitchen, etc. then on lighting a matchstick, an explosive mixture will burst into flame causing fire in the house and can cause serious burn injuries.
In order to prevent this, LPG companies add a chemical ethyl mercaptan which helps in detection of the leakage because of the smell imparted.