A 19-year-old construction worker presents for evaluation of a rash. He notes that it started on his back with a multitude of spots and is also on his arms, chest, and neck. It itches a lot. He does sweat more than before because being outdoors is part of his job. On physical examination, you note dark tan patches with a reddish cast that has sharp borders and fine scales, scattered more prominently around the upper back, chest, neck, and upper arms as well as under the arms. Based on this description, what is your most likely diagnosis?
A) Pityriasis rosea.
B) Tinea versicolor.
C) Psoriasis.
D) Atopic eczema.