Question

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this text is mainly about
a careers for people who enjoy science and medicine,
b colonists who believed that everyone was a doctor,
c health risks people may be taking when they travel,
d diseases in colonial times and how they were treated.

Explanation:

To determine the main idea, we analyze each option:

• Option A: The text doesn't focus on careers in science/medicine.
• Option B: There's no indication colonists believed everyone was a doctor.
• Option C: The text isn't about travel - related health risks.
• Option D: The presence of a mosquito (which can transmit diseases) and the mention of colonial times in the option suggest the text is about diseases in colonial times and their treatment.

Answer:

D. diseases in colonial times and how they were treated.