What Does It Mean That Party Identification Is "A Running

What does it mean that party identification is "a running tally?"

A) It changes dramatically because of things that are happening on a day-to-day basis.
B) People update their views in response to political events.
C) It is unrelated to current political phenomena.
D) It is a deep psychological attachment developed early in life.
E) People keep score of which party is ahead in the polls and often switch sides to be with the "winning team."