In a certain country, individuals tend to change their political affil

In a certain country, individuals tend to change their political affiliation readily from one political party to another. In the past the Union party grew larger because of this tendency, but although most of those who change to a new party affiliation change to the Union party, the Union party has remained about the same size in recent years.

Which of the following, if true, best helps to explain the change in the growth pattern of the Union party mentioned above?

(A) The economy has been prospering recently, and many of those who change party affiliation are upwardly mobile and prosperous.
(B) In recent y~rs those who were previously nonaffiliated have tended to join the Union party if they joined any party at all. '
(C) The percentage of voting-age citizens who change political party affiliation each year has remained constant, and the number of voting-age citizens has remained the same.
(D) The percentage of voting-age citizens who are affiliated with any political party has increased over the last ten years.
(E) Many members of the Union party have abandoned all political party affiliation in recent years.