"The second count alleges a conspiracy to commit an offense against the United States, to-wit, to use the mails for the transmission of matter declared to be non-mailable by title 12, 2, of the Act of June 15, 1917"
The answer is B. He tried to send something through the mail illegally.
In the text they tell us that the first charges that are presented are for trying to cause insubordination in the military and naval forces of the United States, and to obstruct the service of recruitment and enlistment of the United States, which indicates that the three answers A, C and D would go against the ideals of the accused. In addition, the bold lines inform us that the accused tried to use the mail to send confidential information of the United States, which violates a law making it an illegal act.
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