This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable Diseases, Subject name: Social & Preventive Medicine
True about rash of chicken pox- 
Select and explain. 
A. Deep seated, B. Centripetal, C. Affects palm & sole, D. Slow evolution
B: Centripetal
Answer: B: Centripetal 
Explanation: Ans. is 'b' i.e., Centripetal Differences between smallpox and chickenpoxSmallpoxChickenpox1 Incubation:About 12 days(range : 7-17 days)About 15 days(range : 7-21 days)2. Prodromol symptoms :Severe.Usually mild.3. Distribution of rash:a) Centrifugalb) Palms and soles frequently involved.c) Axilla usually freed) Rash predominant on extensor surfaces and bony prominences.a) Centripetalb) Seldom affectedc) Axilla affectedd) Rash mostly on flexor surfaces.4. Characteristics of the rash:a) Deep-seatedb) Vesicles multilocular and umbilicatedc) Only one stage of rash may be seen at one time.a) Superficialb) Unilocular; dew-drop like appearance.c) Rash pleomorphic, i.e., different stages of the rash evident at one given time, because rash appears in successive crops.d) An area of inflammation is seen around the vesicles.d) No area of inflammation is seen around the vesicles.5. Evolution of rash:a) Evolution of rash is slow, deliberate and majestic, passing through definite stages of macule, papule, vesicle and pustule.b) Scabs begin to form 10-14 days after the rash appears.a) Evolution of rash very rapid.b) Scabs begin to form 4-7 days after the rash appears.6. Fever:Fever subsides with the appearance of rash, but may rise again in the pustular stage (secondary rise of fever).Temperature rises with each fresh crop of rash.