Context: Shell's primary business is the management of a vertically integrated oil company. The development of technical and commercial expertise in all stages of this vertical integration, from the initial search for oil (exploration) through its harvesting (production), transportation, refining and finally trading and marketing established the core competencies on which the company was founded. Similar competencies were required for natural gas, which has become one of the most important businesses in which Shell is involved, and which contributes a significant proportion of the company's profits. While the vertically integrated business model provided significant economies of scale and barriers to entry, each business now seeks to be a self-supporting unit without subsidies from other parts of the company.

Question: What is Shell's primary business?
Answer: the management of a vertically integrated oil company

Question: The development of what two types of exptertise established the core competencies on which the company was founded?
Answer: technical and commercial

Question: One of the most important business in which Shell is involved is what?
Answer: natural gas

Question: Each business now seeks to become what type of unit?
Answer: self-supporting

Question: The business model that provided significant economies of scale and barriers to entry is called what?
Answer: vertically integrated

Question: What is the least important business for Shell?
Answer: Unanswerable

Question: What did self-supporting units provide for the company?
Answer: Unanswerable

Question: What types of expertise have been removed from the business?
Answer: Unanswerable

Question: Which stage does not require technical and commercial expertise?
Answer: Unanswerable

Question: What company is moving away from having self-supported units?
Answer: Unanswerable