I think my Proctor was not a real person but a robot. I started with a real human but transferred to something named "something3-Watcher". Is it even possible to get a robot as a proctor?

I got a correct twice, but I agree that it's a terrible question. I got the right because D) has language that's too strong and the last sentence in the stimulus allows the phone to be on speakerphone but still divert attention. Although I get these correct, I absolutely hate questions like this as opposed to 5-star questions.

I didn't even realize they were only comparing elderly people. I choose B because being young doesn't necessarily mean you're more healthy. Perhaps all the young people have cancer and all the old people go to the gym everyday.

But why did JY use conditional logic for eliminating choice A? Was he wrong to do so?

In the video, he used conditional lawgic to justify eliminating A?

You are confusing the concept of a control group and a control variable. This is an observational study, not an experiment.