Final answer:
Marquis' decision to pray during a moment of silence is protected under the First Amendment, which guarantees freedoms of religion and the free exercise thereof.
Step-by-step explanation:
Marquis decided to pray during the moment of silence, which is associated with the First Amendment of the United States Constitution. The First Amendment protects the freedoms of religion, speech, press, and the right to peaceably assemble and petition the government. It explicitly prohibits Congress from making any law that would establish a religion or prevent the free exercise of religion, thereby allowing individuals, including students in public schools, to engage in prayer or other religious activities as long as it is not disruptive or in violation of others' rights.