Honestly, that question could have been labeled just about anything data acquisition related - but they stuck the buzzword "SCADA" in there. It could have been a protective relay.
I think it falls more under CTs and PTs than it does SCADA, honestly. They just mentioned it as a buzzword, in my opinion. If you're going to study up on anything, study up on Current Transformers and Potential (Voltage) Transformers. They *will* be on the test, I'm sure. I think it's highly more likely to see a differential relaying question (using current transformers) on the exam.
In regards to SCADA, there are a few things they might ask, though I doubt it. For example, in SCADA, your resolution of reading depends on your A/D converter and your input voltage range. Maybe they'd ask "A SCADA remote telemetry unit uses a 0 to 5 volt DC input with a 12 bit analog to digital converter. What is the voltage resolution?". That would be a SCADA question. Beyond that, I don't know if they could ask much, as they never delve in to SCADA protocols in the sample exam, comm lines aren't really applicable, computer databases & displays aren't really applicable, etc.