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
In scabies which skin layer is affected? 
Select and explain. 
A. Stratum corneum, B. Stratum basale, C. Stratum lucidum, D. Stratum germinatum
A: Stratum corneum
Answer: A: Stratum corneum 
Explanation: Ans. is 'a' i.e., Stratum corneum After copulation, the male mite dies and the female mite burrows into the superficial skin layer (stratum cornuem) at the rate of 2 mm/day. Female mite lays eggs which hatch into larva, which moulds and mature into adult mites. The mite then burrows into stratum corneum. These burrow is visible clinically as an irregular gray-brown line. Burrow is a pathognomic sign for scabies.