Answer:
D. Thornstan, who is writing a book that will be sold in bookstores
around the world
Explanation:
To be considered as a producer in the market, you need to transform a certain type of raw material into something that other people can consume/enjoy.
In Thornstan case, The blank paper, the ink, and his original ideas are what considered to be the 'Raw Materials'. He transformed those materials into a book with interesting contents for the buyers to consume/enjoy.