How does a photographer create a negative sandwich?

Read this excerpt from when birds get flu and cows go mad! by john diconsiglio. 1986 don’t eat the meat the first diagnosis of bovine spongiform encephalopathy (bse)—or mad cow disease—is made in britain. in the next five years, mad cow will appear in much of europe, including spain, italy, and greece. how is the information in this passage organized? it is sorted by time order. it is sorted using keywords. it is sorted by steps in the process. it is sorted into numbered sections.