Final answer:
John Adams's first choice for Chief Justice in 1801 was John Marshall. Marshall's appointment was pivotal in shaping the U.S. Supreme Court's role and authority, and he served as the Chief Justice for thirty-four years.
Step-by-step explanation:
In 1801, John Adams's first choice for Chief Justice was John Marshall (a). As one of his final acts before leaving the office of President, Adams appointed Marshall, hoping to maintain the Federalist party's nationalist agenda. John Marshall is often credited as the major force in defining the modern court's role in the U.S. governmental system, serving as Chief Justice for thirty-four years.
John Marshall was first appointed as Secretary of State by Adams in 1800 before being appointed as Chief Justice in 1801. His tenure saw landmark cases like Marbury v. Madison, which established the Supreme Court's authority over constitutional questions at the federal level. Marshall's leadership was pivotal in strengthening the role and power of the federal judiciary during the early years of the American republic.