1. Painting A top left shows a farmer family. Painting top right shows a town worker's (blue collar) family. Painting bottom left shows a white collar middle class family and bottom right shows a noble family.
2. You can say each family belongs to a different class based on, one from their dress and second, the surroundings they are in.
3. Painting bottom right shows a noble family. All three shown in the painting are very well dressed indicating they are rich and belong to the ruling class. The furniture they are using appear to be made from solid wood and decorated with engravings.