A physician who delivers babies

Answer: Option B

One word substitute is Obstetrician.

Paediatrician: a medical practitioner specializing in children and their diseases.
Obstetrician: a physician or surgeon qualified to practise in obstetrics.
Gynaecologist: a physician or surgeon qualified to practise in gynaecology.
Psychiatrist: a medical practitioner specializing in the diagnosis and treatment of mental illness.