This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Skin
Collarette of scales is a feature of: 
Select and explain. 
A. Acne, B. Psoriasis, C. Pityriasis rosacea, D. Pemphigus
C: Pityriasis rosacea
Answer: C: Pityriasis rosacea 
Explanation: Pityriasis rosacea