The correct answer is D. Pools were made of independent companies, but trust was not.
Step-by-step 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.