I would have to agree with the previous responder, however both would be acceptable answers. Photography is generally appealing to everyone. Pictures are worth a thousand words but people view photographs in different ways, although not equally. On the other hand, when an instructor is teaching a lesson it is easier for a student to relate to the lesson when there is a picture to accompany it. It basically puts the lesson into perspective and makes it seem real. This often helps the students to gain a better understanding of what they are learning.
The answer would be 2 because, even though both answers are possible, we cannot liberally ascertain that EVERY culture is equally touched by photography. That would be to generalize.
The significance of photographs as a visual text at elementary school is based on the fact that pictures allow for additional observation, helps build schema, provides additional visualization of the topic at hand, and, like you stated yourself, it also illustrates the text and its surroundings.
When a topic is hard to bring from the abstract to the concrete (such as for example, historical events), a photograph definitely helps to add to the learning experience with a factual representation of the event. This will help the student builds create more learning bridges to the lesson.