Which of the Following Statements Best Describes How National Party

Which of the following statements best describes how national party conventions have changed over time?

A) Though national conventions prior to World War II were primarily devoted to debating and negotiating about who the party's nominee would be, today's conventions serve mostly as media events to promote the candidate the party has already selected.
B) Although national conventions prior to World War II were primarily media events to promote the candidate the party had already selected, today's conventions are devoted mostly to debating and negotiating about who the party's nominee will be.
C) There has been very little change in national party conventions over time, as they have always served mostly as media events to promote the candidate the party has already selected.
D) There has been very little change in national party conventions over time, as they have always been primarily devoted to debating and negotiating about who the party's nominee will be.