Final answer:
DeShawn's state uses a closed primary system for nominating party candidates for Senate, where only registered party members can vote in the party's primary elections.
Step-by-step explanation:
DeShawn's state party uses a closed primary for selecting the party's nominee for Senate. In a closed primary, only registered members of a political party are permitted to vote in that party's primary elections. This method prevents members of other parties from influencing the nomination and ensures that the nominee reflects the preferences of party members. The identification of the nomination method is important for understanding the political process and ensuring that DeShawn is informed about the requirements for participation in his state's electoral system.