Katlynn C. answered 05/31/20
Experienced and Award Winning English Tutor
Thank you for your question! In the first part of your sentence, the "these" and "them" do not provide me with a lot of content. However, I am going to answer to the best of my ability.
In my opinion, what makes the underline sentence a transitional sentence is the fact that it is pointing the reader in a different direction. In other words, in the underlined sentence, the author wants the reader to focus on the "challenges", as emphasized by the sentence.
I hope this helps!