What Is Done at the National Party Conventions When They

What is done at the national party conventions when they meet every four years?

A) Delegates are assembled so the party can assess their future political potential based on their writing of the party platform.
B) Presidential and vice presidential candidates are nominated, a party platform is written, and party rules are revised.
C) Candidates are sworn to adhere to both the letter and the spirit of the party platform once they are elected to office.
D) Elections are held to determine the new party leaders, who then appoint the members of the national and state committees.
E) Presidential and vice presidential candidates are nominated, and nominations for state and local party candidates are approved.