Step 1: Concept
The pituitary gland has two distinct lobes (anterior and posterior) that secrete different hormones.
Step 2: Meaning
The posterior pituitary stores and releases hormones produced in the hypothalamus.
Step 3: Analysis
ACTH and Growth hormone are secreted by the anterior pituitary. Thyroid hormone is secreted by the thyroid gland. Oxytocin (and ADH) are the two hormones released by the posterior pituitary.
Step 4: Conclusion
Thus, Oxytocin is the hormone among the choices secreted by the posterior pituitary.
Final Answer: (C)