Final answer:
Ross Perot was the candidate who was nominated by self-announcement, running an independent third-party campaign for president in 1992.
Step-by-step explanation:
Among the presidential candidates mentioned, the one who was nominated by self-announcement was Ross Perot. Unlike traditional candidates who are nominated through a party convention or primary process, self-announcement is a method by which a candidate declares their intent to run for office independently, without the formal backing of a major political party. Ross Perot, a wealthy businessman, made such an announcement for his presidential bid. In 1992, he ran a notable third-party campaign, drawing votes from both liberal and conservative bases, despite not winning any electoral votes.