Hormones that the posterior pituitary secretes are synthesized in the:

The radial artery is one of the major blood-supplying vessels to the forearm and hand.
It can be felt as a pulse near the thumb on the wrist by gently pressing the artery against the underlying bone.
This is the most commonly measured pulse by nurses to assess peripheral pulse characteristics.
Choice B.
Palmar arch arteries are wrong because these are branches of the radial and ulnar arteries that form anastomosis in the palm of the hand.
They are not palpable on the wrist.
Choice C.
The brachial artery is wrong because this is the main artery of the upper arm that bifurcates into the radial and ulnar arteries at the cubital fossa.
It can be felt as a pulse in the antecubital fossa, not near the thumb on the wrist.
Choice D
The Ulnar artery is wrong because this is another major blood-supplying vessel to the forearm and hand that runs along the medial aspect of the forearm.
It can be felt as a pulse on the little finger side of the wrist, not near the thumb.

Hormones that the posterior pituitary secretes are synthesized in the hypothalamus.

They are made by neurons in the hypothalamus and stored and released by the posterior lobe of the pituitary gland, a small organ at the base of the brain.
They regulate water balance, blood pressure, and uterine contraction in the body.
Choice A is wrong because the anterior pituitary synthesizes its own hormones, such as growth hormone, thyroid-stimulating hormone, and prolactin.
Choice C is wrong because the thalamus is not involved in hormone synthesis or secretion. It is a part of the brain that relays sensory and motor signals to the cerebral cortex.
Choice D is wrong because the posterior pituitary does not synthesize hormones. It only stores and releases hormones made by the hypothalamus.