A 29-year-old woman with acquired immunodeficiency syndrome has severe, nonresolving watery diarrhea. It is not gray or greasy. Acid-fast oocysts are seen in the stools. What is the most likely causative agent?
A) Enterohemorrhagic Escherichia coli B) Cryptosporidium C) Enterotoxic Escherichia coli D) Giardia E) Salmonella