Explanation
The section that defines Acid attack in the Indian Penal Code (IPC) is (b) 326A.
Section 326A of the IPC specifically deals with the offense of acid attack. It states that whoever causes permanent or partial damage or deformity to another person by throwing or administering acid on them shall be punished with imprisonment for a term which shall not be less than ten years but which may extend to imprisonment for life, along with a fine.
Therefore, the correct answer is (b) 326A.