7.
A:
1 day in metropolitan areas, 3 days in municipal areas, and 7 days in rural areas
B:
3 days in metropolitan areas, 7 days in municipal areas, and 15 days in rural areas
C:
7 days in metropolitan areas, 10 days in municipal areas, and 30 days in rural areas
D:
5 days in metropolitan areas, 15 days in municipal areas, and 20 days in rural areas
The answer is: B