The primary system that allows voters to register or change their party registration on election day is known as a(n)

Semi-closed primary system

Explanation:

 The semi-closed primary system is also called as the hybrid primary system where the voters are allowed for registering and also change their specific party registration on the election day.

 In the semi- closed primary system, the unaffiliated voters are willing to participating in this system by their specific choice in the voting booth in the congressional elections.

The members of the administrative divisions is also known as the closed primary system.  

Therefore, Semi-closed primary system is the correct answer.

economic