1.
The image is captivating because the simple background puts more focus on the subject. The lighting is very soft and didn't create any harsh shadows throughout the image. The rule of composition shown in this picture is rule of thirds because the subject directly in the center. The subject is conveying a happy emotion.
2.
The background color creates a good contrast between the wall and the subject.
The rule of composition is rule of thirds because of the placement of the subject and Contrast of color because of the transition of colors throughout the picture.
The lighting created a strong light value on the face of the subject. The emotion shown by the subject is joyful.
3.
The photo is captivating because of the centered subject and the interesting background. The emotion conveyed in the photo is simple and happy. The values transition through the subject added both light and dark. The composition showed is the obvious one Rule of Thirds but also Contrast of Color.