Which is one of the reasons to crop a photo?

Cropping a photo primarily involves removing unwanted areas from the image to improve composition or focus on specific subjects. While reducing file size can be a consequence of cropping—since elements are removed and thus the overall resolution and file size may decrease—it is not the primary intent of cropping.

The primary goal is to enhance the visual appeal by adjusting the framing and allowing the viewer to engage more with the subject matter. The other options—enhancing brightness, adding filters, and changing contrast—are more technical adjustments related to the photo's appearance rather than compositional changes. Therefore, while cropping can lead to a smaller file size indirectly, its main purpose lies in composition and not in adjusting the image properties or quality.