Final answer:
Developing a marketing mix is not a step in the strategic/consultative selling model, as it is a broader marketing strategy component. The other provided options are part of the selling model, focused on different aspects of building and executing personal sales strategies.
Step-by-step explanation:
The question refers to the strategic/consultative selling model which is a comprehensive approach to sales that encompasses multiple strategies to understand and meet the customer’s needs. Among the options, letter A) develop a marketing mix is not a step in this selling model. The marketing mix is a broader business concept related to the marketing strategy of a company, and not specific to personal selling, thus making it the outlier.
Whereas, B) develop a personal selling philosophy, C) develop a product strategy, D) develop a relationship strategy, and E) develop a presentation strategy are integral parts of the strategic/consultative selling model. These steps are aimed at cultivating strong buyer-seller relationships based on trust and value, tailoring product benefits to customer needs, and effectively communicating offers to prospects respectively.
In the context of John D. Rockefeller's management strategies, horizontal and vertical integration were indeed methods he employed. The holding company model also factors into his business tactics. However, on its own, social Darwinism is a philosophical concept rather than a direct business strategy applied by Rockefeller, which is a common misconception.