Answer:
It highlights the significance of a key piece of information about deer ticks
Step-by-step explanation:
This paragraph does not describe the treatment of Lyme Disease, it describes its origins. This rules out option 1. The bolded section is turned out to be the true cause of the disease, ruling out option 3.
It is key information about deer ticks, because it mentions they appeared more often where Lyme Disease appeared more often. That is evidence of causation.