Question

the risk to researchers
why is there no health risk for researchers working at the burial site?
plague is now a treatable disease
plague bacteria cannot survive very long in soil
human beings can no longer be affected by the bacteria that cause plague
there are no rats buried nearby and no fleas to carry the disease

Explanation:

• Plague bacteria can't survive long in soil, so researchers at the burial site aren't at health risk from it.
• While plague is treatable, that doesn't directly explain lack of risk at the burial site.
• Humans can still be affected by plague bacteria.
• The presence of rats and fleas isn't the key reason for no risk at the burial site as per the nature of the bacteria's survival.

Answer:

plague bacteria cannot survive very long in soil