Statement — “Large AC rooms are found to contain ~700 ppm CO₂ compared to open areas with ~320 ppm,” reports a survey.\nConclusions:\nI. Indoor plants can help reduce CO₂ levels in AC rooms.\nII. Over time at workplaces, oxygen percentage drops because ~85% of the same air is recirculated inside the room.

Introduction / Context:
The survey merely compares measured CO₂ levels indoors vs outdoors. We must not import solutions (plants) or technical specifics (recirculation percentages) that are absent from the statement.

Given Data / Assumptions:

• Indoor CO₂ ~700 ppm; outdoor ~320 ppm.
• No mention of mitigation strategies.
• No mention of HVAC recirculation shares or oxygen dynamics.

Concept / Approach:
Conclusion I proposes a remedy (indoor plants). While plausible in practice, the statement provides no basis to conclude this. Conclusion II asserts a mechanism (85% recirculation causing oxygen drop) not present in the data. Therefore, neither follows.

Step-by-Step Solution:
1) Identify scope: descriptive comparison only.2) Reject added prescriptions or technical details not stated.

Why Other Options Are Wrong:
Any option granting I/II/Either/Both injects outside knowledge.

Common Pitfalls:
Turning an observation into a recommendation or causal mechanism without textual support.

Final Answer:
Neither I nor II follows.