B) The details about sugar’s dependency on slavery help inform readers about why sugar was inexpensive.
Explanation:
This excerpt from "Sugar Changed the World" states the dark story behind sugar's sweeter taste and its inexpensiveness. It is dark because its taste and availability is made possible by the most brutal labor of millions of slaves. The author's purpose in this passage to establish sugar's dependency on slavery. Hence, option B is correct.
Option A, C and D are incorrect because they state supporting arguments and less important facts.They (A, C, and D) also says nothing about dependency of sugar on slavery (which is important idea of the passage).