Final answer:
Justice Brown quotes the previous court decision to support his argument that courts only enforce political equality, not social equality, adhering to the 'separate but equal' doctrine.
Step-by-step explanation:
Justice Brown likely quotes the previous Supreme Court decision People v. Gallagher during his argument to utilize a legal precedent with the intent to strengthen his own position in the case at hand. When Justices cite previous decisions, they are often looking to stare decisis, a legal principle of determining points in litigation according to precedent. In the context of the provided information, the correct option would be:
A. He uses a previous Supreme Court decision to support his argument that courts can only enforce political and not social equality. This statement aligns with the historical context provided wherein the courts upheld the doctrine of "separate but equal" which focused on political and legal equality, rather than social equality.