The correct option is A Baking soda
The sting of ants contains formic acid. Any acid can be neutralised by adding a base. Baking soda is a base and is capable of reversing the pain, itching and swelling caused by a bee sting. Lemon and vinegar contain acids which cannot nullify the formic acid injected by an ant. Water is neutral in nature. Hence, these three are not used for treatment.