White blood cells use __________ to help identify foreign substances in the body.

• A. antibodies
• B. hormones
• C. enzymes
• D. antigens

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the role of white blood cells in the immune system. White blood cells are responsible for identifying and responding to foreign substances, such as pathogens, in the body.
2. Step 2: Review the function of antibodies. Antibodies are specialized proteins produced by B cells (a type of white blood cell) that bind to specific antigens on foreign substances to neutralize or mark them for destruction.
3. Step 3: Compare antibodies to the other options provided: hormones, enzymes, and antigens. Hormones are signaling molecules that regulate physiological processes, enzymes are proteins that catalyze biochemical reactions, and antigens are foreign substances that trigger an immune response.
4. Step 4: Recognize that white blood cells use antibodies to identify foreign substances by binding to their antigens. Antibodies are the key tools for recognizing and targeting pathogens.
5. Step 5: Conclude that the correct answer is 'antibodies,' as they are directly involved in the identification of foreign substances by white blood cells.