Final answer:
Randall's adoption of three-piece suits in anticipation of his banking career refers to anticipatory socialization, the preparation for future roles.
Step-by-step explanation:
The stage of socialization illustrated by the example of Randall wearing three-piece suits in his last year of college, even before he took a job with a conservative bank, refers to anticipatory socialization. This term describes how individuals prepare for future roles they envision themselves occupying. Much like a couple living together prior to getting married or parents-to-be reading baby care books, Randall is engaging in the behavior and adopting the dress code of his expected role in the professional world. This process involves adopting the norms and behaviors associated with a new status before actually occupying that role, in Randall's case, becoming part of the banking industry, which is known for its conservative dress codes.