Which one term in each of the following includes the other three?
(a) thyroid, ductless gland, thymus, pituitary, ovary
(b) adrenalin, insulin, hormone, thyroxine, estrogen
(a) Thyroid, thymus, pituitary and ovary these all are ductless glands.
(b) Adrenalin, insulin, thyroxine and estrogen these all are hormones.
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