How does Construct handle downscaling with large viewports?

I found plenty of information on upscaling, but not so much with downscaling. If I'm using a 4K viewport (3840 x 2160) and displaying fullscreen on 1080 monitor, how is the downscaling handled?

a) Is everything rendered at 100% to a 4K canvas and then downscaled together 50% to 1080?

b) Or are the objects individually downscaled to 50% and then rendered to a 1080 canvas?

Or some other way...