Which Atmosphere term is correctly associated with key feature: “particles are extremely sparse”, and also with “light gases such as hydrogen and helium dominate”?

Correct Answer: Option C — Exosphere. Exosphere is correct because it is particles are extremely sparse. Exosphere is also associated with light gases such as hydrogen and helium dominate. A further identifying fact is that Exosphere is particles are extremely sparse. Another useful fact is that Exosphere is associated with light gases such as hydrogen and helium dominate. Why the other options are incorrect: Option A — Ozone layer: It is absorbs much of the Sun's harmful ultraviolet radiation and is associated with its depletion increases surface UV exposure; those are the identifying facts of Ozone layer. Option B — Jet stream: It is mainly flows from west to east and is associated with it strongly influences weather systems and aviation routes; those are the identifying facts of Jet stream. Option D — Trade winds: It is deflected westward by the Coriolis effect and is associated with help drive tropical ocean currents; those are the identifying facts of Trade winds. Exam Takeaway: Link Exosphere with “particles are extremely sparse” and “light gases such as hydrogen and helium dominate” for quick revision.