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 the infected flowers researchers picked and tested were close to apiaries.
- All of the honeybees researchers collected were infected with both viruses.
These points indicate a direct correlation between the presence of honeybees and the infection of the flowers, suggesting that honeybees are the source of the viruses affecting those flowers.