For the illustrator to adapt and incorporate photographs into his digital collage, the photographs must have a Creative Commons license that allows for modifications. The two correct answers would be:
-
CC BY - This license allows others to use, modify, and distribute the work, even commercially, as long as they provide proper attribution to the creator.
-
CC0 - This license places the work in the public domain, allowing anyone to use it freely for any purpose, including adaptation.
The other licenses (like CC BY-NC-SA, CC BY-ND, and CC BY-NC-ND) have restrictions that would not allow for adaptation or commercial use.