Explanation:

- Option 1: Pareto

- Vilfredo Pareto is known for his work on elites and the circulation of elites, not for a linear explanation of the evolution of human societies.

- Option 2: Weber

- Max Weber focused on the role of ideas, values, and authority types in social change, not a purely linear evolution.

- Option 3: Spencer

- Herbert Spencer gave a linear explanation of the evolution of human societies. He applied Darwin’s theory to society, suggesting societies evolve from simple to complex in a straight-line (linear) manner.

- Option 4: Sorokin

- Pitirim Sorokin proposed a cyclical theory, not linear, explaining that societies oscillate through different cultural stages.

Correct Answer: Option 3: Spencer