Final answer:
Baker v. Carr argued that the Equal Protection Clause requires a one person, one vote approach to districting.
Step-by-step explanation:
The answer to the question is a) Equal Protection Clause.
Baker v. Carr (1962) argued that the Equal Protection Clause requires a one person, one vote approach to districting. This means that each congressional district should contain roughly the same number of people to ensure that each person's vote in a congressional election is worth as much as another's.