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, pituitary, thymus and ovary are types of ductless glands.

(b) Adrenalin, insulin, thyroxine and estrogen are types of hormones.