For the illustrator to use photographs in a digital collage as described, the photographs would need to be available under licenses that allow for adaptation and commercial use. The two correct answers are:
- CC0 - This license allows for any use without restrictions, including commercial use and modifications.
- CC BY - This license allows users to use, adapt, and distribute the work, including for commercial purposes, as long as they provide appropriate credit to the original creator.
The other options (CC BY-NC-SA, CC BY-ND, CC-BY-NC-ND) either restrict commercial use or do not allow modifications, making them unsuitable for the illustrator's intended use.