Explanation:

- Option 1: Austin

- John Austin was a legal theorist known for his work on legal positivism.

- He focused more on the analysis of law and its structure than on moral philosophy.

- Option 2: Bentham

- Jeremy Bentham was a philosopher known for developing the theory of utilitarianism.

- He proposed that the greatest happiness of the greatest number should be the guiding principle of conduct and legislation.

- Option 3: Both (a) and (b)

- This option is incorrect as the specific statement about the greatest happiness is attributed to Bentham, not both Bentham and Austin.

- Option 4: Salmond

- John Salmond was a legal scholar known for his work on jurisprudence.

- He focused more on legal principles and definitions rather than utilitarianism.