A 33-year-old couple has been diagnosed with unexplained subfertility after 2 years of trying. All investigations (ovulation, semen analysis, tubal patency) are normal. According to NICE CG156, which is the single most appropriate management advice?AStart clomifene citrate immediatelyBAdvise continued regular intercourse every 2-3 days - in unexplained subfertility of 2 years' duration, she should be offered IVFCOffer intrauterine insemination (IUI) with ovarian stimulation as first-lineDRefer for diagnostic laparoscopy to exclude occult endometriosisEAdvise adoption as natural conception is unlikelyCheck my answer