The correct answer is A. Caustic soda.
Sodium hydroxide is a chemical compound with the formula
NaOH. It is a white solid that is highly soluble in water. It is a strong base and is commonly used in industry and in the home.Caustic soda is a common name for sodium hydroxide. It is so named because it is a strong base that can cause severe burns if it comes into contact with skin or eyes.
Caustic potash is another name for potassium hydroxide. It is a strong base that is similar to sodium hydroxide, but it is not as commonly used.
Soda ash is another name for sodium carbonate. It is a salt that is used in many industrial processes. It is not a base and is not as caustic as sodium hydroxide.
In conclusion, the common name for the compound having formal NaOH is caustic soda.