Final answer:
The exceptions to the unit rule in the United States presidential election process are Maine and Nebraska, which use the congressional district method to award electoral votes.
Step-by-step explanation:
The question is asking about the exceptions to the unit rule in the context of the United States presidential election process. The unit rule refers to the winner-takes-all method of awarding electoral votes, where the winner of the popular vote in each state receives all of that state's electoral votes. However, there are two exceptions to this rule: Maine and Nebraska. These states use a different method, called the congressional district method, where one electoral vote is awarded to the winner of the popular vote in each congressional district, and the remaining two electoral votes are awarded to the candidate who wins the state's overall popular vote.