Answer:
a . It shares the detail that the war lasted four years.
Step-by-step explanation:
Paul Janeczko's "The Dark Game: True Spy Stories" is a novel about espionage and surveillance in the world of US politics and security. The book also describes several instances of spy stories from the real top-secret missions undertaken by the US government.
In the given passage from the novel, the author details how devastating the Civil War was for the people of the United States as the number of casualties was more than that of "wars from the Revolution through the Vietnam War." The paragraph reveals how long the Civil War took place, stating that it was "some four years later" after General Lee surrendered to Ulysses Grant.
Thus, the correct answer is option a.