Multiple choice

The endocrine system produces

  1. hormones

  2. enzymes

  3. killer T cells

  4. fibrins

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A Correct answer
Explanation

The endocrine system consists of glands that secrete hormones directly into the circulatory system to regulate distant target organs. Enzymes are catalytic proteins, killer T cells are part of the immune system, and fibrins are involved in blood clotting.