What is the purpose of the underlined sentence in the passage? A
to prove that fossil fuels are responsible for climate change

B
to explain why Earth’s average yearly temperature is rising

C
to clarify that greenhouse gases are not always bad

D
to provide a quote from a climate-change expert

C

Explanation:

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.