Deductive reasoning.
Deductive reasoning is a type of reasoning where a general fact is broken down into a more specific case to make an inference. This general fact can be a broad branch of knowledge then gets into its parts that may comprise this broad knowledge.
The correct answer is B. Oxygen.
Oxygen, as a part of the atmosphere, also participates in UV protection, besides being necessary for breathing.
Ribose, phosphate groups, and adenine.