How are fossil fuels formed?
O
A. They are made of melted ice caps.
O
B. They are grown on farms.
O
C. They are made of decayed organisms.
O
D. They are created by volcanoes.

They are made of decayed organisms

Then it's c

Explanation:

C

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.