During active labour cervical dilatation per hour in primi is: .
Labour is said to active when:

Cervix is dilated to at least 3 – 4 cm.
Regular uterine contractions are present.
Rate of dilatation is at least 1.2 cm/hr for nulliparous and 1.5 cm/hr for parous women.
1.2 cms
1.5 cms
1.7 cms
2 cms