Question

Read the excerpt from “Tools of the Spymaster."

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.

Which statement best expresses the central idea of the excerpt?

James Jay was a spy for the Americans and had knowledge of chemistry.
James Jay’s invisible ink system allowed Washington to write secret messages.
James Jay believed secret messages that became visible because of heat were not secure.
James Jay’s system required two chemicals for writing and reading invisible ink messages.

Answer 1

James Jay's system required two chemicals for writing and reading invisible ink messages.

Step-by-step explanation:

This is the central idea of the text, as the text mostly focuses on the process behind decoding the messages, which requires a second chemical. Every other answer is an assumption or an afterthought.