Voters Who Were Between 18 and 24 in 1984 Are

Voters who were between 18 and 24 in 1984 are more likely to identify as Republicans today, while those of the same age range in 2008 are more likely to identify as Democrats.What variable or factor is likely to have been highly influential here?

A) The fact that parents of most of these voters were of the opposite party
B) The high economic growth rates that voters saw during those years, under presidents of different parties
C) The early presidential election experiences of these voters, who saw Republican Ronald Reagan win in 1984 and Democrat Barack Obama win in 2008
D) Parental influence, since most adults of child-rearing ages were Republicans in 1984, and most were Democrats in 2008