Final answer:
The pain of labor may cause a stress response in the mother that results in increased blood pressure and elevated cortisol levels, but not the contraction of uterine muscles, as these are caused by oxytocin. The correct combination is (i) a and b.
Step-by-step explanation:
The pain of labor can cause a stress response in the mother, resulting in increased blood pressure, elevated cortisol levels, and the contraction of uterine muscles. When a fetus exerts pressure on the uterine wall during labor, this induces the production of the hormone oxytocin. Oxytocin stimulates the contraction of the uterine wall muscles, which is necessary for the delivery process. Additionally, the stress of labor can cause a physiological stress response, leading to an increase in blood pressure and the release of stress hormones, such as cortisol. However, the contraction of uterine muscles is directly caused by oxytocin released in response to the stretching of the cervix, not by a stress response. Therefore, the correct combination in response to labor pain causing a stress response in the mother is (i) a and b: increased blood pressure and elevated cortisol levels.