Which of the following groups contains only peptide or polypeptide hormones?

• A. Insulin, glucagon, parathyroid hormone, and oxytocin
• B. Cortisol, aldosterone, glucagon, and estrogen
• C. Thyroxine, epinephrine, prolactin, and testosterone
• D. Progesterone, calcitriol, aldosterone, and cortisol

Answer: (A)