Logic Chain (ish) question

blackhawksfan

Hello,
I've got a common question about linking up a logic chain. I just re-watched the video lesson but it's not precisely the answer to my question. Any help is appreciated!

If you have:

Premise: A ---> B ----> C
-------------------------------------
Conclusion: D ---> C

Is it correct to try to make D ---> A and D ---> B (either one works, along with their contrapositives) OR would it be correct to make A ---> D and B ---> D?

My question is from PT 47 section 3, number 21. According to the video, it is the former method, but I remember doing it the other way sometimes. I got the Q right doing it in my head but it'd be great to confirm it. Thanks again

CFC152436

Definitely the first way. If you use the second method, the only valid conclusion you could draw would be "C some D"

blackhawksfan

Thank you so much!