Answer:
D). To persuade young men to join the army.
Step-by-step explanation:
While creating a literary or speech, the author always has a pre-defined purpose which is also known as the intent or reason for which he/she has created that particular work. It could be to entertain, inform, persuade, or merely share an event with the audience.
As per the given excerpt from president McKinley's speech, the chief aim is to 'persuade or convince young men to join the army' as the author intends to encourage the youth to serve as volunteers in the United States army. The speaker(president) 'by virtue of power vested in him' finds it 'fit to call forth the young men' to be the part of army in order to 'carry into effect the purpose of his resolution(125,000 volunteers)'. Thus, option D is the correct answer.