Final answer:
Diversification is the marketing strategy that involves adding unrelated products to a company's product line. Social Darwinism does not represent a management strategy used by John D. Rockefeller, who instead used horizontal integration, vertical integration, and the holding company model.
Step-by-step explanation:
While implementing a marketing strategy, diversification involves adding products that are unrelated to the present product line. This is often pursued to reduce risks by spreading interests over different areas and can tap into new markets. Diversification stands in contrast to strategies such as penetration, which seeks to increase market share for existing products; specialization, which focuses on a narrow product line; and acquisition, which involves buying other businesses.
In the context of John D. Rockefeller's management strategies while building his empire, social Darwinism does not represent a management technique he used. Rockefeller is famous for his use of horizontal integration, where he bought out competitors; vertical integration, taking control of the entire supply chain; and the holding company model, where a corporation owns shares of other companies to form a corporate group.