Explanation:

- Correct Answer: Option 3, Saint Simon

- Henri de Saint-Simon was a French aristocrat, socialist, and writer.

- He collaborated with Auguste Comte.

- Their joint work, "Plan of the Scientific Works Necessary for the Re-organization of Society" (1822), laid the groundwork for sociology.

- The work outlines the law of the three stages, which is central to Comte's philosophy.

- Option 1: H. Spencer

- Herbert Spencer was an English philosopher.

- Known for his contributions to social theory and for coining the term "survival of the fittest."

- Option 2: Hobhouse

- L.T. Hobhouse was a British sociologist.

- He contributed to the development of liberal social theory.

- Option 4: A. Ferguson

- Adam Ferguson was a Scottish philosopher.

- Known for his work in ethics and social philosophy.