A group of 50 people attended a cookout.  Ten days later, several people develop abdominal cramps and diarrhea.  An investigation of this outbreak considers a variety of causal agents, including parasites.  Among the following parasites, which one is the LEAST LIKELY to have caused the outbreak?

(a) Cyclospora cayetanensis
(b) Entamoeba histolytica
(c) Cryptosporidium sp.
(d) Taenia solium