Fever is initiated by chemicals called:

• A. interferons
• B. antibodies
• C. pyrogens
• D. complement proteins

Answer: (C)

Verified step by step guidance

1. Understand that fever is a physiological response to infection or inflammation, and it is triggered by specific chemical signals in the body.
2. Identify the types of chemicals listed: interferons are proteins that interfere with viral replication; antibodies are immune proteins that recognize antigens; complement proteins assist in immune defense.
3. Recognize that pyrogens are substances that cause fever by acting on the hypothalamus to raise the body's temperature set point.
4. Differentiate between endogenous pyrogens (produced by the body, such as cytokines) and exogenous pyrogens (originating from pathogens).
5. Conclude that among the options, pyrogens are the chemicals responsible for initiating fever.