John Snow is known as the father of epidemiology.
In this essay "On the Mode of Cholera" he used both reasoned argument along with documentary evidence to show that cholera spread from person to person.
He gave examples of rows of houses on opposite sides to each other, and how all of the members in one row contracted cholera, while only one person on the opposite row contracted the disease.
The answer is D. This is because it mentions that in EARLY AMERICA they were already using presidential campaigns and it’s still happening today.
This one.
"No change came over the old face. As though vast calculations were going through her head, she watched all the pattern shifts."
The status of the scientist is that she watches the patterns shift.