Passage Summary: A certain enzyme is the key to our mouth's defense system. Since we are learning how to boost that enzyme back to normal, the author thinks we can finally wipe out gum disease for good.

Conclusion: Restoring the enzyme cathepsin C to normal levels will enable the total elimination of gum disease.

Reasoning: A deficiency in this enzyme prevents the body from fighting the infections that cause gum disease, and scientists are close to finding a way to fix that deficiency.

Analysis: The author is making a massive leap from 'fixing a major cause' to 'eliminating the disease entirely.' For this to be true, we must assume that cathepsin C deficiency is the only insurmountable obstacle to curing the disease. If there are other causes of gum disease that don't involve this enzyme, restoring it won't lead to total elimination. Look for an answer that bridges the gap between the enzyme's function and the absolute success of the treatment.