A 50-year-old woman has chronic plaque psoriasis affecting 15% of her body surface area and significant impact on quality of life despite potent topical corticosteroids and vitamin D analogues. What is the most appropriate next step in management?AContinue topical therapy onlyBStart narrowband UVB phototherapy or systemic therapy under specialist supervisionCStart long-term oral corticosteroidsDUse coal tar onlyEDo nothing as psoriasis is benignCheck my answer