Answer:
When the author says “[Cora] Martin is part of a small army of young volunteers,” she uses the literary device called:
Metaphor.
Explanation:
Here Martin is metaphorically compared to a part of the small army of young volunteers. Therefore, a metaphor is a figure of speech that compares two things that are not alike, but have something in common. A simile compares two things using 'like' or 'as' while a metaphor compares two things by stating that one is the other.
