Why Is the Inability of a Party Leader to Control

Why is the inability of a party leader to control a candidate's usage of a party label in elections important?

A) Election monitors have a more difficult time differentiating fake ballots.
B) Women candidates have a more difficult time being nominated in primary elections.
C) Candidates run individualistic campaigns and not partywide plans.
D) Parties do have the ability to control the usage of their label.
E) Presidents can utilize this feature to generate more institutional strength.