Answer:
Element
Explanation:
Element is a pure substance that cannot be broken down.
Trace fossils include footprints, trails, burrows, feeding marks, and resting marks. Trace fossils provide information about the organism that is not revealed by body fossils. Trace fossils are formed when an organism makes a mark in mud or sand.
The answer is:
<u><em>A) Methane</em></u>
because if u picked anything else the reaction would not happen