The two pieces of evidence from the text that best support the inference that honeybees—not bumblebees—are responsible for infecting the studied flowers are:
- All of the honeybees researchers collected were infected with both viruses.
- All the infected flowers researchers picked and tested were close to apiaries.
These pieces of evidence suggest that since honeybees are consistently infected with viruses and the infected flowers are also closely associated with areas where honeybees are present, honeybees are likely the source of the infection for the flowers.