Impact craters caused by meteorites smashing into Earth have been found all around the globe, but they have been foun...

Andrew on September 5, 2022

Necessary or Sufficient

I chose D but it seemed like this one was a "strengthen with necessary" answer. Can someone explain how I've misinterpreted it and why its sufficient or can a "strengthen with necessary" sometimes be the correct answer if a "strengthen with sufficient" is not an available option.

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Emil on September 6, 2022

Hi Andrew,

It is possible that an assumption is both sufficient and necessary- that is, it is something the author must also believe, and if added to the argument, it will make it valid.

D actually does make this argument valid- there is a possibility that the distribution of meteors is not even, in which case the conclusion is not necessarily true. D closes off that possibility.

Andrew on September 6, 2022

Thank you Emil!