I mentioned that in another discussion but the provided PDF reference "AWS Multi-Account Security Strategy" is seriously outdated. It dates from 2017. Even at re:Invent 2018 the multi-account strategy presented was much different and it has been update again at re:Invent 2019. The reference should be updated to point to this video – which is a must watch:
AWS re:Invent 2019: Architecting security & governance across your landing zone (SEC325-R2)
Reiterated from other post. Some of these items are on our list to update, but do realize that just because AWS comes out with new services, questions on the exam don’t change overnight. It’s quite common for exam questions to show up on the exam out of the vast database of questions which cover a wide range of "generations" of recommended approaches. This is why we don’t immediately rewrite course content when new services or white-papers are released.