The correct answer is D. Pools were made of independent companies, but trust was not.
Explanation
Pool and Trust are two terms used in the business world to refer to the relationships between the companies of a specific business. The term pool refers to the agreements made by several companies to avoid unfair or unequal competition between them and to control the market for a product among all while maintaining their autonomy. On the other hand, the term trust refers to the union or agreements that establish companies to work as one to control a market. According to the above, the correct answer is D. Pools were made of independent companies, but trust was not.