Chemical messengers that are transported in the bloodstream are called:

Correct option is A

→ Hormones are chemical messengers released by endocrine glands and transported through blood to target organs.
→ They regulate growth, metabolism, reproduction, and homeostasis.
→ Essential for coordinating physiological processes in fishes.
Information Booster:
→ Key reproductive hormones include estrogen, progesterone, and androgens.
→ Hormones act even in very low concentrations due to receptor specificity.
→ Disturbance in hormones affects spawning and maturation cycles.
Additional Information (Other Options):
(b) Cells, (c) RBCs, (d) WBCs: Blood components, not chemical messengers.