How is C wrong?

@Anna, the trick is in the "necessary and sufficient" relationship between the factors here. In other words, mutual respect and affinity are "necessary" for a relationship to be long lasting (without them the relationship will fail), but they are not "sufficient" to guarantee that a relationship will be long lasting (even if a relationship has mutual respect and affinity, it can fail due to other circumstances). In practical terms, I had a roommate in college who was a close friend. We had an affinity for each other, and we had mutual respect for each other. We had a close personal relationship and even took a few trips to visit grad schools together. However, when we moved away after college, our friendship failed. We are not enemies, by any means, but we haven't talked more than a few times in the intervening decade, which would suggest that despite having the "necessary" ingredients for a successful interpersonal relationship, those ingredients were not sufficient to guarantee the success of that relationship in the long term. This type of question will come up a lot, and the trick is often recognizing the difference between what is sufficient and what is necessary. Get that principle mastered, and you're well on your way to mastering the LSAT. I hope that helps.

But the paragraph says, if its to endure it must have MS & A. Choice C) Says if you have both, the relationship will last long. Isn't that evoking necessary to conclude sufficient?

Ignore the below.

@BradG, it sounds like you may have answered your own question. If you'd like any additional clarification, please let us know—we're here to help!

I got this answer wrong, because I made the same mistake as discussed above. However, after looking at it carefully, I think I realized how I was supposed to diagram it. T (trust) and MR (mutual respect) -----> L.L.R (long lasting relationship) the rule for and/or is to flip it to the other and then reverse and negate as usual, so no L.L.R -----> no T or no MR so, that is what A states, correct? by using the word solely, it shows the contrapostive correct? I hope I didn't make this question too confusing. I just wanted to know if I processed and worked it out correctly, thank you!

can someone please answer my question