Final answer:
Congress delegates authority to administrative agencies for rulemaking, adjudication, and investigation, but it does not delegate the power to create laws, which is known as legislation.
Step-by-step explanation:
Congress delegates substantial authority to administrative agencies in several areas, including rulemaking, adjudication, and investigation. These agencies are responsible for implementing and enforcing laws by creating detailed rules and regulations, conducting administrative hearings, and investigating breaches of those laws. However, one authority that Congress does not delegate to administrative agencies is legislation. The power to create laws - legislation - is the sole responsibility of Congress itself, as delineated in the U.S. Constitution. While agencies can issue rules and regulations, these are based on existing legislative frameworks and do not constitute legislation in and of itself.