Step 1: Understanding the Question
The question asks to identify the offence under the Information Technology Act, 2000 that carries the most severe punishment, up to life imprisonment.
Step 2: Analyzing the Offences and Penalties under the IT Act
(A) Stealing an e-mail password: This would likely fall under sections related to hacking (Section 66) or identity theft (Section 66C), which carry punishments of imprisonment up to three years.
(B) Fraudulent publication: This could relate to various sections like cheating by personation (Section 66D) or publishing obscene material (Section 67), which have varying but lesser punishments than life imprisonment.
(C) Ethical hacking: This is not an offence; it is the practice of hacking to identify vulnerabilities with permission, for defensive purposes.
(D) Cyber terrorism: This is defined under Section 66F of the IT Act. It covers acts committed with the intent to threaten the unity, integrity, security, or sovereignty of India or to strike terror in the people. Given its grave nature, Section 66F specifies that whoever commits cyber terrorism shall be punishable with imprisonment which may extend to imprisonment for life.
Step 3: Final Answer
Among the given options, cyber terrorism is the most serious offence and is the one that carries a maximum penalty of life imprisonment under the IT Act. Therefore, option (D) is the correct answer.