Answer: True
A topic sentence refers to the main idea of the paragraph. Usually, a topic sentence is found on the first line of the paragraph wherein it tells something about the entire content of the paragraph. The main idea of the paragraph or the topic sentence must be following by supporting evidence or statements. The topic sentence should be general and at the same time specific. It is general in the sense that it must be able to present the entire subject of the paragraph but specific enough to be understood by readers.
What are the sentences available prior to the question?
Answer:
by explaining how a captive’s condition was assessed.
Explanation:
The author developed the central idea that transporting enslaved captives was a trade just like any other in "Captain Canot" or "Twenty Years of an African Slaver" by explaining how a captive’s condition was assessed.
Most trades or all trades have profit as its main driving force, and profit cannot be made if the goods you sell is not good enough, so slave masters had to assess a captive's condition to find out if he was good enough to make a profit or not just like any other trade.
I think the answer is: direct object