Inhaling helium from a pure helium pressurized tank can cause something called an 'air embolism'. This is eventually a bubble that was trapped in a blood vessel, and therefor blocks it. The blood vessels can then rupture and hemorrhage.
Short answer: The results of breathing in 100% pure helium is asphyxiation, which eventually causes death.
I hope this helps! (If this was a question which had multiple choice answers, feel free to post them in the comment section and I would be more than happy to give you a direct answer to the test.)
