Which of the following is NOT a part of the excretory system?

Option 1 -> Kidney filters blood and produces urine, core component of excretory system.

Option 2 -> Urinary bladder stores urine before elimination, part of excretory system.

Option 3 -> Thyroid gland produces hormones (T3, T4) and belongs to the endocrine system, not excretory.

Option 4 -> Urethra is the tube that carries urine out of the body, part of excretory system.

Hence, Option 3: Thyroid gland -> The thyroid gland is an endocrine organ located in the neck that regulates metabolism through hormone secretion, and has no role in waste excretion -> correct