What is the cause of most cases of pyelonephritis?
A. Genetic disease
B. Ascending infection by E. coli
C. Viral infection
D. Presence of virulent bacteria in the blood
2. What usually initiates acute appendicitis?
A. Severe diarrhea
B. Rupture of the appendix
C. Eating a low-fiber diet
E. Obstruction of the lumen of the appendix