【填句补文】Though little research has been carried out about how exactly the sunspot will negatively harm the health of the people. ________. So, scientists warn that people going outdoors should be careful to protect their exposed skin and eyes with clothes, umbrellas and sunglasses from the strong sunlight rich in ultraviolet rays.
A
Ionosphere is high above the earth.
B
If the lights in your house keep flickering, blame frequent sunspots.
C
According to a research conducted by the Russian scientists from 1957 to 1960, the frequency of earthquakes can be linked to the movement of the sunspots.
D
A paper published by a North Korea observatory says that sun storms may cause an increase in the incidence of heart disease and skin disease.
