Choice C is the best answer because it most logically completes the sentence about the influences on Banisadr’s work. In context, “It is by no means” followed by “unimportant” conveys how it is relevant to recognize Bosch’s influence on Banisadr. The text points out that the artist himself cites Bosch as an inspiration, and then goes on to claim that The Epic of Gilgamesh has had a more significant influence than Bosch. 

Choice A is incorrect because “substantial,” which means weighty or meaningful, incorrectly suggests that it wouldn’t be meaningful to acknowledge Bosch’s influence on Banisadr. The phrase “indeed, Banisadr himself cites Bosch as an inspiration” doesn’t support this suggestion. Choice B is incorrect because “satisfying,” which means pleasing, incorrectly suggests that it wouldn’t be pleasing to acknowledge Bosch’s influence on Banisadr. The phrase “indeed, Banisadr himself cites Bosch as an inspiration” doesn’t support this suggestion. Choice D is incorrect because “appropriate,” which means suitable, incorrectly suggests that it wouldn’t be proper to acknowledge Bosch’s influence on Banisadr. The phrase “indeed, Banisadr himself cites Bosch as an inspiration” doesn’t support this suggestion.