Question

__ energy sources are formed by geologic processes acting over millions of years, while __ fuel sources are created or replaced much faster.

answer options:
select one of four
renewable, nonrenewable\twind, solar
solar, fossil\tnonrenewable, renewable

Explanation:

Nonrenewable energy sources (like fossil fuels) are formed by geologic processes over millions of years. Renewable energy sources (like solar, wind) are replenished much faster. So the first blank should be "Nonrenewable" and the second "renewable".

Answer:

D. Nonrenewable, renewable