The correct answer is A. Carbonic acid.
Carbonic acid is a weak acid that is formed when carbon dioxide gas is dissolved in water. It is the main component of carbonated beverages, such as soda and beer. When carbon dioxide gas is dissolved in water, it forms carbonic acid. This acid is what gives carbonated beverages their fizzy taste.
Sulphuric acid is a strong acid that is often used in industrial processes. It is not used in carbonated beverages because it is too dangerous.
Acetic acid is a weak acid that is found in vinegar. It is not used in carbonated beverages because it does not give them the desired fizzy taste.
Citric acid is a weak acid that is found in citrus fruits. It is sometimes used in carbonated beverages to give them a tarter taste. However, it is not the main component of carbonated beverages.
In conclusion, the addition of carbonic acid adds fizz to soft drinks.