Explanation
Correct answer: D.
Choice D is the best answer because it most effectively illustrates the claim that the speaker in the poem "We Are Marching" predicts future success. To say that someone will "never know" an experience—like defeat, or being unsuccessful—is to indicate that they will never personally have that experience. Thus, when the speaker says that the marching group "shall never know defeat," the speaker is predicting that the group will experience only success in the future.
Why the other choices are wrong
Choice A
Choice A is incorrect because the quotation presents a question about an activity already taking place (marching), not a statement about future success. The speaker is asking if the sound of marching feet is being heard.
Choice B
Choice B is incorrect because the quotation directs an immediate action instead of making a prediction about the future. The speaker is telling people to "get in line," or to join the march that’s already happening.
Choice C
Choice C is incorrect because the quotation describes a past action instead of making a prediction about the future. The speaker is stating that those in the march have "answered duty’s call"—that is, that they have acted out of a sense of duty.