What is the most appropriate first-line intervention?

A 29-year-old woman presented with primary infertility, having had unprotected sexual intercourse for 15 months. Menarche had occurred at the age of 13.5 years. Her menstrual cycle was irregular, occurring every 20C60 days. There was no history of galactorrhoea. She denied abnormal hair growth.

On examination, her body mass index was 28.9 kg/m2 (18C25) and she had normal secondary sexual characteristics. Her visual fields were full to confrontation.

Investigations:

serum androstenedione12.8 nmol/L (0.6C8.8)

serum oestradiol205 pmol/L (200C400)

serum testosterone2.4 nmol/L (0.5C3.0)

serum sex hormone binding globulin23 nmol/L (40C137)

serum follicle-stimulating hormone4.3 U/L (2.5C10.0)

serum luteinising hormone8.5 U/L (2.5C10.0)

serum prolactin420 mU/L (<360)

hysterosalpingogrampatent fallopian tubes

partner’s semen analysisnormal sperm count and motility

What is the most appropriate first-line intervention?
A . cabergoline
B . human chorionic gonadotropin
C . human menopausal gonadotropins
D . metformin
E . orlistat