To support the inference that honeybees—not bumblebees—are responsible for infecting the studied flowers, the following two pieces of evidence from the text are most relevant:
- "All of the honeybees researchers collected were infected with both viruses."
- "All the infected flowers researchers picked and tested were close to apiaries."
These statements imply that the honeybees, which were found to be infected, are associated with the infected flowers that were also located near the apiaries.