All of the above and none of the above.
Deer are funny creatures. I have had deer walk across a field and come to the spot where I walked across the field to my stand stop and smell like a dog at my tracks. Then walk on unconcerned and pick an eat in the field and turn around and walk back across to the exact spot where they stopped and smelled unconcerned just a few minutes ago. When they get to this spot they look like they have run into an electric fence. They jump back and their fur bristle on their back and they take off like a race horse.
I once had a deer that must have spotted me move while I was in my tree house stand,(4'X4' with a roof, built in a big pin oak tree) that is on the edge of a big field that had soy beans at the time in it. 210 yards away in the wood line across the field I saw a deers right antler, ear and eye while scanning with my field glasses. This buck was standing behind a big pine tree 10 yards deep in the woods from the edge of the field. It was about 30 minutes before dark in the evening. I watched this deer until it got too dark to see and it never moved. The next evening about the same time as the day before I was watching this spot and I caught movement a little deeper in the woods and this buck came to the same spot behind that tree and stopped and never moved until it got too dark for me to see. The next evening which was my last day on this hunting trip and I needed one more deer for the freezer. I decided that if that deer came back and stood in that spot watching my stand that evening and did not move into the field for a shot. I was going to shoot him right through that eye that I could see. My custom 25-06 Rem 700 had a Leupold 3-9X50 scope on it with duplex cross hairs. When sighted in for a POI 3" high at 100 yards for a point blank zero of 350 yards that the bullet would not be above or below 4". I could place where the top part of the heavy part and thin center line meet of the vertical part of the cross hair on something the size of a pop bottle cap at 200 yards and hit it dead center. I had ranged to that big pine exactly 210 yards and I knew I could hit that deer in the eye. Sure enough that deer showed up about 30 minutes before dark and I let him stand there for about 15 minutes and he did not move. I got a steady rest across my 2X6 shooting rail put the junction of the heavy and light part of the vertical part of the cross hair on the bucks eye and squeezed the 2 1/2 pound trigger and BOOM and I heard the bullet SMACK. I got out of the stand and by the time I got across the field to the big pine it was almost dark but there laid a good size 7 point buck with his rack cocked sideways and his right eye was gone and the back of his head was a mess. 117 gr Sierra leaving the muzzle at 3100 fps will really mess up a deers head. He was good eating though.
I have had deer trail me just like a dog and walk right up to my stand.
I have had deer see me and stand their watching me for quite a while not moving an eye lash. Some of them even watch me as a slowly raised my rifle and killed them.
This past season. One afternoon I walked into one of my box shooting house stands and while unlocking the lock on the door I dropped the lock and it banged loudly on the wooden steps. When I got into the stand and was taking off my butt back it slipped out of my hand and banged loudly on the floor. I picked it up and put it in it's place. Then as I picked up my rifle and was loading it I dropped one of the rounds onto the floor and as I leaned over to pick it up I bumped with my head a 4" wide board that I use to rest my elbow on when shooting and it fell out of the stand and crashed to the ground. (Ever have one of those days
?) When I got the rifle loaded I turned to place it up on my shooting rail and there in the middle of the path looking right at me was this big doe. I just put the cross hair on her chest and BOOM. I guess I should just beat and bang and make all the noise I can because it seems to bring the deer to me.
Other times I am sure that deer have seen me blink my eyes and they have bolted.
I have found that deer many times won't believe their eyes or their ears but they always believe their noses and are gone like a shot.