Ergometrine is commonly used for :: (A) PostPartum Hemorrhage, (B) To shorten  2nd stage of labour, (C) Dysmenorrhea, (D) Toxemia of pregnancy
Answer is A. Obstetric indications of ergometrine (Ergonovine):

To control and prevent Postpartum hemorrhage. It is given at the time of delivery of the anterior shoulder.
After Caesarean Section/instrumental delivery - to prevent uterine atony.
To ensure normal involution in multipara.