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: Medicine
True about HSP -a) Palpable purpurab) Kidneys commonly affectedc) C-ANCA positived) Thrombocytopenia 
Select and explain. 
A. ac, B. a, C. ad, D. ab
D: ab
Answer: D: ab 
Explanation: None