What is the biggest challenge facing the book publishing industry today?

Explanation:

Getting people to read the book

if a publisher distributes its books

whether online or bookstores, the challenge is getting the book to stand out for people to read because any book that does not stand out will not attract any readers at all.

Fake reviews a lot of published work has fake reviews this makes it more difficult for people to trust a particular book and read and any journal, article, book that is not trusted cannot be read or purchased. Fake reviews can have a detrimental impact on a business.

Inability to locate target users

Target users are the people that buys a product the most if they cannot be sited and located selling the product becomes a problem for a publishing industry.

i would say b. research typically uses a variety of sources