This question is missing the excerpt. I've found it online. It is the following:
James Jay's invisible ink did not become visible by heating. As he described it, his ink "would elude the generally known means of detection, and yet could be rendered visible by a suitable counterpart." Jay's invisible ink consisted of two chemicals. An agent used one chemical to write an invisible message. To read the message, the reader had to brush a second chemical on the paper; that chemical made the message visible. The two-bottle system, supplied by Jay, gave Washington the secure form of writing that he wanted.
Answer:
The statement which best expresses the central idea of the excerpt is:
B. James Jay's invisible ink system allowed Washington to write secret messages.
Explanation:
Options A and C have information that we can assume after reading the passage, but that is not explicit in it. Therefore, they cannot refer to the central idea. We can eliminate those options.
<u>Option D mentions the two chemicals required for writing and reading the messages. Even though that piece of information is discussed in the excerpt, it serves more as an explanation of the central idea. In fact, the central idea itself is that Washington was able to write secret messages because of James Jay's invisible ink. That is what the passage is ultimately about. The author is merely explaining how that ink works when he mentions the chemicals. Thus, we can eliminate letter D and choose letter B as the correct option.</u>
