Why Did Direct Primaries Not Immediately Alter Presidential Politics

Why did direct primaries not immediately alter presidential politics?

A) The costs of administering primary elections were high, leading many states to abandon the process.
B) Too many candidates were actively campaigning for primary votes, preventing the emergence of a majority winner.
C) Citizens rejected the reform, favoring the more democratic processes of King Caucus.
D) Partisans resisted the direct primary's binding of delegates to the primary election outcome.