D.) The Senate rejects a justice nominee.
The president has the right to nominate cabinet members, Supreme Court justices, and federal staff members. All nominations need to go through the Senate to approve.
To prevent presidential domination, the Senate must approve nominations made by the president. If this power did not exist, the president would be able to appoint whomever they please into very powerful positions. Nominees go in front of an approval committee and are require to answer questions about their position, background, and/or viewpoint before the Senate approves or denies a nomination.
