Question

Why are some chemical substances, like oil and coal, considered nonrenewable?

the process that forms them stops working after a decade
the process that forms them has not worked for millions of years
the process that forms them is very fast
the process that forms them is very slow

Answer 1

The process of the formation of coal and oil is a very gradual and slow process.

Step-by-step explanation:

The process of the formation of coal and oil is a very gradual process that takes up to millions of years.