A 40 YO lady with diarrhea of 3 weeks

A 40 YO lady presents with diarrhea of 3 weeks duration, stools are brown , watery. Patient denies fever, chills, and tenesmus. She recently returned from a 2 week vacation in South America, one week into her vacation she developed cramps and diarrhea took Loperamide with partial relief. Examination was essentially unremarkable.
What is next step in management
A. Stool for leukocytes
B. Stool culture for enteric pathogens
C. Stool for Ova and Parasites
D. CBC with differential
E. None of the above