Question

secretion of oxytocin is increased by dilation of the cervix decreased extracellular fluid (ecf) volume increased prolactin levels increased serum osmolarity

Explanation:

Oxytocin secretion is regulated by a positive - feedback mechanism. During childbirth, as the cervix dilates (stretching of the cervix), sensory impulses are sent to the hypothalamus, which stimulates the posterior pituitary to release more oxytocin. Decreased ECF volume mainly affects the secretion of antidiuretic hormone (ADH) rather than oxytocin. Prolactin is mainly involved in milk production, not directly in regulating oxytocin secretion. Increased serum osmolarity is a major stimulus for ADH secretion, not oxytocin.

Answer:

dilation of the cervix