them is always the objective form of they, so "them" can never function as the subject; these/those can either be adjectives (these books) or pronouns which can be used as either subject or object (These are broken; He broke these). You can say "He broke them" which makes perfect sense, but you can't say "Them are broken".

Coming back to the question, both these and those in this case are correct. However, "including/included among" is redundant. If something includes, it's among the set. So A and C are out.

D wins over E because of correct idioms: "threat of" and "sales of"

B is wrong b/c which is modifying the "company" rather than the challenges

Ok, got it. Thanks so much for the explanation, very helpful.