Right, thanks for pointing that out. Maybe I could have been more clear about that in my first post. One of the incorrect answers in the OP was "a. It causes involuntary hyperventilation". Which sounds like a CO2 issue to my ear.
This is a common misconception. Hyperventilation is not caused by excess of CO2, instead it is a condition where CO2 level falls too low...
See the explanation here:
What Causes Hyperventilation?
When there is too much CO2 what you get is dyspnea, which is substantially exactly the opposite of hyperventilation, albeit most people, not knowing the meaning of technical terminology, call it hyperventilation.
This ignorance of technical terminology is a problem against which I am fighting, for example I hate people confusing the viscosity of a lubricant with its density.