Question

Use the sources to answer the question.
Source 1: When the wolf population in Yellowstone National Park neared zero, the grazing herds
rose up to 35,000 animals. When grazing herd numbers rise too high, it can impact the
environment negatively.
Source 2: Over 150,000 people from around the world come to Yellowstone National Park each
year specifically to see wolves. This brings in nearly $35 million in revenue for the states that
support the park.

In the 19th-and 20th-centuries, widespread efforts were made to reduce the number of wolves at Yellowstone National Park. Furthermore, grazing herds sharply rose.

In the 19th-and 20th-centuries, widespread efforts were made to reduce the number of wolves at Yellowstone National Park. As a result, grazing herds sharply rose.

In the 19th-and 20th-centuries, widespread efforts were made to reduce the number of wolves at
Yellowstone National Park. Again, grazing herds sharply rose.

In the 19th-and 20th-centuries, widespread efforts were made to reduce the number of wolves at Yellowstone National Park. On the other hand, grazing herds sharply rose.

Answer 1

The sentence with "As a result" is best supported by the sources.

Why: Source 1 directly links low wolf numbers to a large rise in grazing herds (when wolves neared zero, grazing herds rose to about 35,000), so stating that the herds rose "as a result" of efforts to reduce wolves correctly expresses that causal relationship. Source 2 is about wolf-related visitation and revenue and does not affect the causality between wolf reduction and herd increases.

Notes on the other options:
- "Furthermore" merely adds information but does not state the causal link as clearly.
- "Again" is a repetition, not explanatory.
- "On the other hand" implies a contrast, which is not supported by the sources.