Because it is direct contact of the molecules in the air and the land that are touching.
Carbohydrates, polymers, proteins, and nucleic acids.
These are, well, large organic molecules that are synthesized from multiple identical subunits, as questioned above.
Hope this helps!
The person above is correct :)
A scientific theory is an explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment.
D, a logical interpretation of an observation, basically guessing with some prior knowledge backing your thinking up.
