Choose the correct one-word substitute for: “A government controlled by the rich and powerful.”

The correct option is Plutocracy.

Let's break down the meaning of each word provided in the options to understand why Plutocracy is the correct choice:

1. Plutocracy: A form of government or society ruled or controlled by the wealthy/rich and powerful individuals (derived from the Greek words ploutos meaning wealth, and kratos meaning rule or power).

2. Oligarchy: A small group of people having control of a country, organization, or institution (not necessarily defined strictly by wealth).

3. Bureaucracy: A system of government in which most of the important decisions are taken by state officials rather than by elected representatives.

4. Technocracy: A system of governance where decision-makers are selected on the basis of their expertise in a given area of responsibility, particularly with regard to scientific or technical knowledge.

Therefore, the one-word substitute for "A government controlled by the rich and powerful" is Plutocracy.