What Is the Primary Difference Between an Open Primary and a Closed

What is the primary difference between an open primary and a closed primary?

A) An open primary permits anyone to participate, while a closed primary requires participants to be eligible voters.
B) An open primary is conducted in public with the media present, while a closed primary is conducted in private.
C) An open primary allows anyone to participate regardless of party affiliation, while a closed primary requires party affiliation.
D) An open primary is free for eligible voters to participate in, while a closed primary charges a fee in order for voters to participate.