Solution:

As you can see in the given explanation that the rope is indeed straight. But since we are looking at it with a pillar in front and the rope is angled, it is creating an illusion that the rope is not straight. The moment we remove the pillar, it is as straight as it can be.

Solution:

You can see that it appears like both of the fingers are in a straight line and they are pointing on the same point. But when we meet the diagonals, you can see that they are not. The finger A is pointing a bit above from the center point. Surprising right?

Solution:

You probably thought that the right one is at the center right? But the moment we remove the spherical lines, you know that you are wrong. So basically, in this figure, the spherical lines are creating an illusion that the right one is the center dot as we are seeing things relatively to the lines and not the circle.

Solution:

The moment we remove the background circles, you find out that it indeed is a square by all means. So, you know that the whole illusion was created due to the concentric circles. Due to them it appears that the straight lines of the square are bent from the middle. It is crazy right?

Solution:

Indeed, the red lines are straight lines and they are parallel as well. Removing the background, it is pretty clear. But with the background, they appeared to be moving away from each other at the ends. This is because the lines in the background were pointed and moving away from each other.

Solution:

Removing the background lines, it is evident that the circle a real one and it is not distorted as it had appeared with those lines. The pattern behind made the circle appear distorted to our eyes. This is one of the popular example of shape-distortion riddles.

Solution:

The big square is a real square with straight lines. The same can be said for the mini squares created by the lines inside the square. All the lines are perfectly straight and parallel (vertical with vertical and diagonal with diagonal). The diagonal lines in the middle makes those straight lines appear distorted from the middle. However you can see that it is actually not after removing the background.

Solution:

This is one the tricky one. Your eyes can never believe that they are actually of same sizes. Even if you see our explained image, you might not believe. This is the beauty of perspective, you can almost create magic. Coming back to the point, yes they indeed are of same sizes as you can see in our rough measurement.

Solution:

The distorted lines in the background are the culprit behind the distortion we see in the squares. But if we remove those lines, you can see that these are actually three true squares with perfect straight and parallel lines.

Solution:

Yes the given two circles are horizontal. But they don't appear to be. The reason behind this is the diagonal lines which are bent in the opposite direction. This is the reason why we take the horizontal squares to be slightly tilted in opposite directions. The moment we remove the background lines, you can clearly see that they are horizontal.