Security can mean either one. There is actually no official difference recognized by IRCC between security screening and "basic security check". They simply refer to it as "security". You do need your CBSA notes to find out if i is a comprehensive security screening.
I prefer not to talk about nationality as many people from my country have got their PPR without any delay or SS, and I thank you for your respect for my decision not to say anything about nationality

As to travel history, I do have a lot of international travels but most of them were EU countries, US, Singapore and Australia. I have never been to any "flagged countries". I think the slection criteria for SS are a combination of all factors instead of any single one, so saying a person is under SS purely because of his nationality or travel history is not reasonable.