Final answer:
Francis should upload his book on the Project Gutenberg platform to freely distribute it while retaining the copyright.
Step-by-step explanation:
If Francis wants to freely distribute his picture book while retaining the copyright, he should upload it on the Project Gutenberg platform. Project Gutenberg allows creators to share their works with the world while maintaining their rights. It is a digital library that offers free access to books that are in the public domain or have explicit copyright permissions.
Option a) Amazon Kindle Direct Publishing is a platform for selling books, but it does not allow creators to retain copyright while offering free distribution. Option c) Creative Commons is not a publishing platform, but rather a license that creators can use to indicate the permissions and restrictions on their works. Option d) Public Domain Review is an online journal that explores public domain works and does not allow uploading of new content.