Oxytocin Helps Initiate Labour in Mammals

Oxytocin helps initiate labour in mammals. During labour and delivery, the contraction of uterine muscles increases the release of oxytocin. This is an example of

A) a hormone that is involved in a positive feedback loop.
B) signal transduction immediately changing gene expression in its target cells.
C) a negative feedback system.
D) the key role of the anterior pituitary gland in regulating uterine contraction.
E) a hormone that acts in an antagonistic way with another hormone.