Answer:
C, careful
Step-by-step explanation:
The passage explains that people who don't Excercise much should get a calm dog and people who do exercise should get a lively dog, it is letting you know to be careful. If you don't exercise, you would want to be careful so you don't get a really energetic dog. Or, if you do exercise, don't get a calm one because then it would slow you down.
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