I've been using Cache/IRIS for nearly 20 years, and I didn't notice when they snuck in the SELECT JSON_OBJECT() function. That's going to start getting a lot more use now I know it exists! 

Another really useful feature is the ability to access fields across relationships using the -> operator. This saves all the time and effort of writing join statements if table relationships are in place. 

Cheers

And then the question is, does it have to be a correct answer? 
Because if not I'm going to be getting lots of points very quickly ;) 

It's a great exam. I'm not just saying that because I helped develop it, but it has some great questions and topics on it that really make you think. 
I can't say I enjoyed the process of taking my last Intersystems exam, (not this one), but I certainly enjoyed the feeling after I passed it. :)
It's great to get that validation that you do actually know what you're talking about!