Final answer:
Comiket requires that all works sold must be self-produced and self-published, and this policy is indeed true.
Step-by-step explanation:
The statement that all works sold at the Comic Market (often known as Comiket) must be self-produced and self-published is true. Comiket is a biannual doujinshi (self-published works) fair in Tokyo where artists and creators sell their own original manga, novels, music, games, and other forms of art. It’s a key platform for indie manga artists and is hugely popular among fans of the anime, manga, and gaming communities.