Answer:
Because people did not know that yellow fever was caused by the bite of an infected mosquito, they assumed incorrectly that people could catch the disease through touch. To help control the disease, letters were cleaned with vinegar before being sent. This did not work, because it was a false cause-and-effect relationship.
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(c) is the right answer
Answer:
Topic control occurs when the main or assigned speaker manipulates the discussion in order to maintain its flow without moving away from or changing the topic.
Explanation:
The answer to this is the glossary.