Answer:
The nuclear fuel used in a nuclear reactor needs to have a higher concentration of the U 235 isotope than that which exists in natural uranium ore. U235 when concentrated (or "enriched") is fissionable in light-water reactors (the most common reactor design in the USA).
Explanation:
This kind of damage occurs repeatedly, it may lead to permanent damage to your lungs that could cause a lower quality of life. Ozone may aggravate chronic lung diseases, such as emphysema and bronchitis. Scientists are concerned that repeated short-term damage from ozone exposure may permanently injure the lung
It seems like the answer is C, you really just need to use the process of elimination.