When assessing a woman in the first stage of labor, which clinical finding will alert the nurse that uterine contractions are effective? a. Dilation of the cervix
b. Descent of the fetus to -2 station
c. Rupture of the amniotic membranes
d. Increase in bloody show

Dilation of the cervix

Explanation:

A true  First stage of Labor starts with regular contractions causing the cervix to efface out and dilate, and an assessment of the woman will tell if her contractions are effective by the cervix opening from 0 gradually to 10 cm

Descent of the fetus to -2 station. Station in pregnancy is a measurement o indicate the decent of the baby to the pelvis. -2 station tells us the baby still lies above the ischial spines before the pelvis.

Rupture of the amniotic membranes also called  water of water can occur either at the start of labor or during labor, it is not an indication that contractions are effective

Increase in Bloody  indicates that labour is about starting and does not indicate that contractions are effective.

d, i believe because of it's activity level