Final answer:
The statement about the $300 law refers to conscription during the American Civil War, underscoring resentment over the draft and the class disparities, leading to the New York City Draft Riots. The correct answer is option C.
Step-by-step explanation:
The statement "...that 300-dollar law has made us nobodies, vagabonds and cast-outs of society, for whom nobody cares when we must go to war and be shot down." refers to conscription during the American Civil War. It highlights the resentment and desperate circumstances of those subject to the draft, including riots in New York and the underlying issues of class and race. The ability of the wealthy to pay for substitutes with a $300 exemption fee further fueled the perception that the conflict was a rich man's war, but a poor man's fight, leading to violent and racially charged riots such as the New York City Draft Riots in July 1863.