During which stage of labor does effacement of the cervix occur?
a. dilation stage
b. expulsion stage
c. placental stage
d. gastrula stage
e. blastocyst stage

a. dilation stage

Explanation:

Dilation stage -

The phase in the pregnancy ,

Cervix is present in the bottom portion of the uterus , this area opens when the  women delivers a baby via vagina , is called the process of cervical dilation .

During the process of labor , the cervix opens up to release the head of the baby , which opens up to 10 centimeters , and the process is done automatically in most of the cases .