Final answer:
Martin Luther King Jr. advances his viewpoint by quoting religious texts and invoking moral principles, especially those rooted in Christian ethics, to underscore the immediate need for civil rights and social justice.
Step-by-step explanation:
Martin Luther King Jr. utilizes his profound personal connection to the church to enhance his argument in "Letter from Birmingham Jail" by primarily invoking moral principles and referencing religious texts. This is best represented by Option 1: By quoting religious texts and invoking moral principles.
He directly appeals to the moral and ethical responsibilities of his audience, many of whom are part of the religious community. King challenges religious leaders to embrace social justice as a central tenet of their faith, criticizing those who suggest that civil rights activists wait for a 'more convenient season' to fight for their rights.
He also draws from biblical figures, such as Apostle Paul and Jesus Christ, to underline the righteousness of his cause and to articulate the urgency of taking direct action against racial injustice. King's letter emphasizes that waiting for gradual change is no longer acceptable, and he calls for immediate action grounded in the ethical and moral imperatives that are part of the Christian tradition.