1. I think this black covering is used as the same purpose as making the inside of a camera black so that it cannot reflect the light many times and also only let light that comes through the pupil to be focused on the retina.

2. I think it is vitamin A that is related with the eye. Lack of vitamin A could cause night blindness. Food that contains vitamin A such as egg yolks, butter, cheese, liver, carrot, sweet potato, milk, mango, and spinach is good for the eye. I also heard that vitamin B2, C, D, and E influence the health of our eyes.

1. I am not sure of what this black covering is(I do not think it is mentioned in the book), but I think it must help the images to focus on the retina, so that we can see clearer images.

2. There are many types of vitamins related with the eye, such as vitamin A, B, C, D, E, and more. Vitamin A helps the surface of the eye become more effective in preventing bacteria and viruses and reduces the risk of eye infectious diseases.Vitamin D plays an important role in preventing eye aging. The other vitamins mentioned above also play an important role in maintaining the health of the eye.

1. I think it is the iris, and it opens and closes to change the size of the pupil.

2. Vitamins A, C, D, and E are related to the eye. Especially, Vitamin A is very important for the eye. It helps the retina and makes the eye sight intact.