Answer:
B. Sedimentary basins
Explanation:
Petroleum can only accumulate in a petroleum source with organic matter, which sedimentary basins can provide.
Answer: Hydrogen
Explanation:
Hydrogen gas (H2) is a molecule, but not a compound because it is made of only one element. Water (H2O) can be called a molecule or a compound because it is made of hydrogen (H) and oxygen (O) atoms.
Answer:
C. Organisms are grouped by species
Explanation:
In Ecology, organisms are grouped by species.