Confused

Yes same please

Yes, can some one explain.

Hi the author is trying to prove that despite an increase in the reported number of tornados, the actual underlying number hasn't changed and what has changed is that we got better at finding tornados. C strengthens the argument by telling us that no such change has occurred in the number of big tornados. This would mean that all of the increase has come from small tornados. Since it's very unlikely that big tornados would ever go unnoticed, this seems to support the idea that what happened is that we are just noticing more small tornadoes that would have otherwise gone unreported.