<prompt> A 12 year old boy had severe vomiting and diarrhoea. He was brought to the hospital bacause of severe oliguria. He was given IV fluids and furosemide without any diuresis. Blood beichemistry revealed : Urea 120 mg and serum creatinine 4 mg. The most likely diagnosis is -Preneal azotemiaHaemolytic uraemic syndromeAcute glomerulonephritisAcute tubular necrosis  <response>: Ans. is b i.e., Hemolytic uremic syndrome 