Step 1: Understanding hormone classification.
Hormones are classified based on chemical nature into peptide, protein, amine, and steroid hormones. Each type has distinct structure and function in the body.
Step 2: Peptide hormones.
Peptide hormones are short chains of amino acids. ADH (vasopressin) and oxytocin are examples of peptide hormones.
Step 3: Protein hormones.
Protein hormones are larger polypeptides with complex structure. TSH and ACTH are classical protein hormones secreted by the pituitary gland.
Step 4: Amine hormones.
Amine hormones are derived from amino acids like tyrosine or tryptophan. Melatonin and thyroxin are examples of amine-derived hormones.
Step 5: Steroid hormones.
Steroid hormones are derived from cholesterol. Estrogen and testosterone belong to this category and regulate reproductive functions.
Step 6: Final conclusion.
Thus, correct matching is A2, B1, C4, D3.