Can anyone explain why answer choice D is a sufficiency-necessity mistake? I'm a bit confused #help

I think these are more so strategies to use when we are trying to weaken or strengthen an argument. For example, if we are doing a weakening question, we can see whether one of the Hypotheses explanations can help us weaken the example they are providing.

"Answer choices will often declare those hypotheses to be either true or false." Can we see an example of this? I'm confused on how we will know if an alternate hypothesis is true or not.

#help

I'm stuck on understanding the breakdown for question 18. I guess I am still having a hard time differentiating the necessary from sufficient when the sentences are more complex.

#help

What makes answer choice C correct? #help